I guess I see things a little different than the others. I think your stance is too wide. I feel that most raw squats should be just wider than shoulder width. 2 big fundamental mistakes to me are the knees coming in on the transition up, and losing some upper back tightness thus causing some rounding. I think the lose of tightness is an air issue. Some people will tell you to hold the air in the chest, others in the stomach. I am a stomach guy, but either way holding that air in should help with the rounding. As far as the knees go, just keep forcing them out.
The depth is great, walk out looked good, and the weight was light for all the small errors that are going on. Keep up the great work!