The new Vizio M-Series for 2015 is a good budget 4k TV, and in some cases, even better than the P Series. As long as you don't expect a perfect TV, it is a good purchase.
For the price, the new M Series for 2015 is a really good 4k TV. It upscales 1080p better than the P Series, however, its local dimming is not as good. The two main downsides to this TV are the long motion blur trail and the loss of saturation at an angle.
This TV's contrast ratio is great. The local dimming feature did have an effect on the black level of our checkboard pattern, but it also affected the white boxes, which isn't good.
As with the E series, the local dimming dims the highlights. It darkens brighter objects on the screen considerably when they are alone on a dark background. In our test video, you can see that the white dot is darker than it should be. Of course, there is less blooming that way, but it's not good to have the object appear too dark. The P Series handled our test pattern better, and it has more zones, too.
This TV loses saturation when you are off-axis.
Update 01/06/2017: We have changed the methodology of testing. Since this is an old TV which we don't have anymore, we extrapolated the results from 2016 TVs.
We had to increase sharpness to 25 for our 480p test, as otherwise it was really blurry. See here for more details. The P Series didn't have that issue. The noise reduction features work, but they are not very effective. Also, setting 'Reduce Block Noise' to 'High' resulted in a drastic loss of sharpness, so we used Medium instead.
Unfortunately, like the P Series, this TV has a very long trail following moving objects. In our picture, you can see that the brighter trail even continues outside the picture. This shouldn't be an issue with normal content, but it could be a problem for video games.
The input lag is really low when using the HDMI 5 input and turning on 'Game Low Latency'.
It doesn't support chroma 4:4:4 unfortunately at any resolution/refresh rate. This doesn't matter for movies or even video games, you will only see a difference for a PC monitor. 4:2:2 works though.
1080p @ 120fps works (although only for the 60" model and up), which is great for gaming on a PC.
Relatively good frequency response and loudness. However, at higher volumes, the frequency response gets worse and pumping artifacts may be present. The bass extension is not the best.
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