As the OP in your quote did, I also when to an AT&T store and compared the 820 to the 8X. This is what made me decide to switch, on top of the few problems that have been reported with reception and battery. Plus, the Nokia apps (which I've never been able to play with before) were pretty fun.
The 820's screen, though not as high of resolution as I'd like, is absolutely vibrant when compared to the 8X. Looking at the 8X with the 820 next to it, with the same theme and apps running, there's no comparison. The 8X looks washed out and the 820 pops. Very vibrant.
Some display enthusiasts may say that it is over saturated, but I personally think it just adds to the wow and pop factor of the phone. Immediately after this, I went home, cancelled my preorder on the 8X and ordered the 822. I know I'll be very happy with this phone until the next "amazing" WP8 phone comes along.