I bought this TV a week ago, and it is great for the money.
I have no input lag problems at all, and i game on my tv all the time. XBONE and PC both, and have seen no problems.
I turn off every motion enhancement option there is, so none of that crap is on. Once all that is off, it runs great, the picture is good, its sharp as my computer monitor, and has great colors with lots of options.
Im still lurking here until someone with some calibration tools runs a full calibration and posts the settings they used. I am mostly eyeballing it, and have it looking very nice. I can tell it isnt perfect, but it is very good.
I tried the Sharp 60" that Best Buy had for the same price, and it was complete garbage. the only way to turn off the soap opera effect was to turn on their game mode, which jacked up all the colors, and removed a large chunk of the customization options. It was never clear, and had terrible screen uniformity.
This TV has its drawbacks, as any 55" for 799 does.
Its viewing angles arent great. Its definitely not an IPS panel, but nothing in this price range is, so i had to deal because my budget was maxed for now.
It also doesnt have local dimming, and it is edge lit.
This is not a knock on the TV, those are negatives that come along with the price range.
Overall, I am very happy with this purchase, and will be keeping this one. It is well worth the $799 price of admission.