I've been using 12.10 for about two weeks now with no problems. The whole time I have been using Gnome 3. Then suddenly the system spontaneously rebooted. When it came back up there were lots of obvious, seemingly random graphics bugs. Here's a screenshot:
What your seeing is just an empty workspace with one of the stock wallpapers right after log in.
Changing the background several times will cause it to randomly display correctly/incorrectly. The graphics get borked on individual windows from time to time. I haven't been able to reproduce this with Classic Gnome or Unity, but this happens every time with Gnome 3. I really like Gnome 3 and would like to keep using it, but for now I'm stuck with Unity.
Here's some more info about my system:
- Model: Dell Precision M4600
- Memory: 7.8 GiB
- Processor: Intel® Core™ i7-2640M CPU @ 2.80GHz × 4
- Graphics: Gallium 0.4 on AMD TURKS
- OS type: 64-bit