The Samsung H6400 LED TV is the same TV as the H6350, but with 3D, a better remote, and a slightly different design. The picture quality is the same, which is really good, apart from the limited viewing angle.
Look wise, the Samsung H6400 is almost exactly the same as the Samsung H6350. However, there is a clear border added around the frame (see following picture). That piece is flimsy and a bit useless.
The uniformity of gray is more problematic, but in this price range, you can't get much better than this. You will need to upgrade to the Samsung H7150 for better uniformity.
It has a semi-gloss finish, so the reflections are more blurred than on the glossy screen of the pricier Samsung H7150. It reflects a little bit more, though, but it is definitely not an issue.
Samsung's smart TV interface is great, with tons of apps and features. It is a lot faster than Sony's, especially for big USB drives. Check out our full review of Samsung's 2014 Smart TV platform.
The remote alone is worth the upgrade, compared to the cheaper Samsung H6350, as long as you plan on using the smart TV features a lot. You can control the cursor by just pointing at the TV.