I got my 16GB N7 about a week ago. I noticed the middle-left side of the glass starting to lift off its plastic frame 3-4 hours after unboxing, under "heavy exploration" (every feature enabled, continuously downloading/installing/trying apps) workload.
Other than that, I do not see any obvious other problems with the N7, though I would like it to run a little cooler. The bottom-right corner in landscape mode gets rather warm while running Tegra games.
I have one major pet peeve about the soft-keys and games: very easy to accidentally swipe system keys and get kicked out of games in titles like Fruit Ninja, Glow Hockey, Cut The Rope, etc. A method for locking/unlocking soft-keys is needed, something like a "lock" icon to lock/hide it and tapping opposite corners or center+corner to unlock.