My blue 32gb seems to have no major issues so far. (It FINALLY came yesterday)
No hinge noise, no whiny screen. The virtual button mapping works great, as does the physical button mapping. No flaking paint.
I have 3.2.0 as my base firmware, and it came precharged. Has excellent battery life. I was up till 3am setting it up (draining the battery to 8% before charging it back up), and I used it since about 7pm last night. It's managed an overnight charge fine (use my own charger). Doesn't feel hot when I use it.
(It handles reicast games without any so much as a hiccup. I love it!)
The diagonals DO work on mine. But as others have said they are a little spongy, though I can pull of a shoyruken about 60% of the time, so it's fine for stuff like contra. (I think it also depends on what emulator/game you use. I was using the pre-built FBA KOF 2000, and it played awful, yet the built-in SFA3 and Jojo was fine, as was the .emu series of emulators I prefer to use)
EDIT: The wifi is servicable. Even with a weak signal I can manage about 1-2mb download speed. Better than my PS3's wifi speed. (which is godawful) No loose battery or speaker crackling. Reboots fine. (Fast shutdown speed. Takes about a minute or two to boot up)