How much do you expect out of a television that costs $680 for 65-inches and $580 for 55-inches? If it supports 4K and comes with important game-mode features like auto low latency (ALLM) and variable refresh rate (in this case AMD Freesync), what else does it need? Those are the questions you're going to have to answer for yourself when considering the Vizio MQ6 Quantum television. 
Even for its extremely competitive pricing, I still have certain expectations when it comes to gaming performance and overall features. I want good color reproduction, HDMI 2.1, and a good range of viewing angles. The MQ6 has those. I also expect support for up to 120Hz, solid HDR performance, and decent black levels. The MQ6 doesn't deliver those.
It feels like a television that may have made one too many concessions in order to meet a price tier Vizio really wanted to be in.
As a result, the television offers a mixed feature set that will only appeal to a specific subset of customers looking for a gaming television. It's not a bad overall television, but many gamers – especially those who also expect it to be a great movie-watching television – will be disappointed by its offerings and performance nonetheless. 
Vizio MQ6 – Design and Features
Vizio has been absolutely slaying it in recent years when it comes to the look of its displays, and the MQ6 is no exception. For the purposes of this review, we had the 55-inch model. From the front, this is a very pretty television. The top, left, and right bezels are thin and nearly nonexistent while the bottom features a sleek one-inch-tall bump that frames the screen nicely, and is home to the Vizio logo in the lower right hand corner.
The feet are made of plastic, and while they didn't feel great out of the box, once they're on the television and the whole setup is on a media console, they look the part. 
The backside of the television, which few will often see, is rather thick of a modern 2021 television, but it's not what I would call "ugly." It's fine, and at least it's not just a large, rounded bulge that seems to be the default for most manufacturers. The power cable is permanently affixed to the back of the TV on the left side (when facing the MQ6) while the three HDMI 2.1 cables (one of which supports eARC) are on the right side.
Overall, the Vizio MQ6 features a very simple design that looks really nice.
Vizio MQ6 – Remote
Voice control finally comes to Vizio, and the wait was worth it. Vizio's implementation of voice control into a remote that looks very similar to last year's designs is a welcome addition, and in testing it worked great and very rarely misunderstood me. Voice control makes browsing YouTube, Netflix, Amazon, and other streaming services so much easier than the previous method of manually punching in letters with the navigation buttons. Once you move to voice control, you never want to go back.
The new voice control button slides between the back and closed captioning buttons and above the volume rocker, which makes it easy to find at just below dead center on the remote.
I personally like Vizio's remote because it doesn't waste space with unnecessary buttons and functions. While some people like the larger remotes with lots of classic inputs, I find that 99 percent of the time, I just need volume, voice control, and navigation buttons. Everything else is superfluous. 
Vizio includes six pre-installed shortcut buttons which may change over time, but IGN's review unit featured Peacock, Netflix, Amazon Prime Video, Disney Plus, Crackle, and Tubi.
Vizio MQ6 – Software and Interface
Vizio wonderfully overhauled Smartcast last year and the platform is still great. The interface is snappy and there are a ton of streaming apps to choose from. One note for those who have never used Smartcast before: there is no "marketplace" to download apps. Everything the TV can have is pre-installed, so if you don't see a service listed, it isn't supported on the platform. 
While Smartcast does come loaded with most of the apps customers will be looking for, it still doesn't have everything. Missing last year and still missing in 2021 are either Cruncyroll or Funimation, the top anime streaming apps. This is not going to be a big deal for many people, but if you are trying to stay caught up on One Piece or rewatch Naruto, you'll have to find another way to get it on screen. Luckily, the MQ6 does support Airplay and Google Cast.
Vizio MQ6 – Picture Quality
While the MQ6 looks nice and has great features, the picture quality is where that $680 price for 65 inches starts to show itself. You can only get so much for that low of a price.
The color is pretty good (Vizio promises 75% of P3 color gamut which is great for a TV of this price) and that is likely due to the use of Quantum dots on this panel, which is what the "Q" stands for in the television's name. Color tonality also seems improved, as there was not any issue with the lean towards magenta that the P-Series Quantum from last year had. The color isn't going to win any awards, but most customers looking for a TV in this tier will be overjoyed with the quality.
But as solid as the color reproduction is, there are other issues.
First, Vizio doesn't publish how many local dimming zones the MQ6 has, instead just referring to it as a "full array" backlight. In practice, there do not appear to be very many of them and they also appear rather large, as the television has some serious halo issues. You won't notice it too much when playing video games, but if you are ever watching anything in ultra wide format with captions, you're going to see a halo of light around those bright white letters. To illustrate, just looking at the "no input detected" screen should give you an idea of how bad the situation is on the MQ6.
Second, it does have some light stuttering that is usually easy to ignore, but it can be seen in slow-panning shots in low frame rate footage (like the 24 frames per second that is common in Hollywood films). I didn't notice it much at all in gaming, gratefully.The panel does have a hard time with moire, though. Moire is a "wavy" visual phenomenon that occurs when there are closely-packed vertical lines in an image, the MQ6 will show them to some degree in any setting I tried. The television's default picture mode will make them unbearable, but once you turn down the artificial sharpening and move from Standard to Calibrated modes, the moire is a lot less obtrusive. Still, it's there.
Third, the black levels aren't great which means overall contrast is what I would call "middling." It's not by any means bad, but you will notice that scenes that should be deep black will shade more towards very dark grey or even have a bit of a blue hue to them, which can lead to a bit of a washed out look. That said, this is actually ok for competitive games where you don't want shadows to be completely lost and I found games like Apex Legends to actually benefit from this. Coming from a monitor that I specifically tune to have weaker contrast so that I get a more even look at a scene, the MQ6 looks a bit better actually. For movies though, especially those in Dolby Vision or other HDR modes, it's not the best.
That brings up the fourth issue: dynamic range. Especially in gaming on the PlayStation 5, the MQ6 absolutely struggled to properly display a range of lighting conditions in a single scene. Specifically in The Last of Us Part II, which I tested in the new 4K at 60 frames per second mode on the PlayStation 5, the strong mix of bright sunlight shining down through a dark forest or the shadows of a destroyed building looked akin to trying to immediately adjust your eyes in bright sunlight after sitting in a dark closet for half an hour. This issue was present both with HDR on and off. 
The MQ6 struggled to display highlight detail at the same time as shadow detail, which meant that either the highlights were totally blown out and devoid of detail, or the shadows became very dark as the television attempted to bring that detail back. While both occur, it's more highlights that are a problem than shadows.
I think what's worse than the loss of detail, though, is having to endure watching the MQ6 attempt to adjust its backlight in real time during a game. Whenever a mixed lighting scene appeared, the television would take a few seconds to adjust brightness in a scene – which involves over-brightening shadows and then toning them back right after as it tries to darken highlights and then bring them back to a correct exposure – which is immersion breaking and visually annoying as exposure levels would jump around as I tried to navigate an area.
I will say this issue was not present in every game I played and was most dominantly an issue in The Last of Us Part II. I tested this on other displays to make sure it wasn't an issue with the game itself, but no other television or monitor exhibited this phenomenon.
Finally, the screen itself is very, very reflective which means it is a glare magnet. It's also not particularly bright, so you'll get the most mileage out of the MQ6 in a dark room.
It's not all bad though, as the panel uniformity issues as well as poor viewing angles that I noted in last year's P-Series Quantum model appears to at least be improved. The MQ6 panel has some minor uniformity issues (our unit had a darker lower left hand corner for example) and I found that while sitting dead-on straight to the television was always best, slightly angled viewing situations were not nearly as bad as they have been on past televisions. Extreme angles are still a no-no, but slight angles are tolerable.
Vizio MQ6 – Gaming Performance
While the MQ6 has three HDMI ports and all of them are HDMI 2.1, the panel's limitation to 60 hertz means that the only benefits gamers will see involve ALLM and Freesync, though the benefits of variable refresh rate are curtailed by that frame rate cap.
As far as 60 frames per second gaming goes though, the MQ6 handles them like a champ. I tested Apex Legends, The Last of Us Part II, and Destiny II on the television and all of them felt snappy and responsive. Other than the HDR issues I note above, the MQ6 is great for those who don't see the benefit of exceeding 60 frames per second gaming. Those folks are the ones who predominantly play single player games, and for them the MQ6 will work well.
Vizio MQ6 – Sound Quality
Most sound out of modern televisions is bad, but the MQ6 takes the cake here: sound quality is awful on this television. I always recommend getting some kind of external sound system and in this case it's a must: this might be the worst sounding television I've reviewed in some time. Not only is audio totally bereft of any low-end, the overall EQ seems to be off. I don't have much else to say: get a sound bar.