The Sony X830C doesn't have good picture quality. It reflects too much light in a bright room, and with the lights turned off, the blacks are gray. At least it maintains good color accuracy when viewed at an angle.
The colors are great when you view them off-axis. You will perceive the same picture quality even when you're sitting at quite a wide angle.
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.
Its level of motion blur is good. The setting to control the backlight is a nice feature (see here for pictures), too.
The input lag of the Sony X830C is 36.8ms in Game mode. While this isn't particularly great, it is low enough for most people.
Just like with last year's Sony TVs, 1080p @ 120Hz produces little artifacts (lines), but this shouldn't be too bothersome while gaming.
Update: With the new firmware update PKG2.463.0010NAB, This TV now supports 4k @ 60Hz @ 4:4:4. To enable this, go to Settings - External Inputs - HDMI Signal Format - Enhanced (new).
Note: Sound Quality test for TVs reviewed before 2017 was performed at 75dB, 85dB, and Max SPL. Starting 2017, the target SPL levels have been changed to 70dB, 80dB, and Max dB SPL.
OK bass extension and frequency response under comfortable listening levels. However when the TV gets loud, and it does get loud, there is a significant decrease in the frequency response and pumping may be present.
Contrary to the X850C, the X830C only comes with a basic remote.