What machine (and config) are you using?
I've read some of the other comments below and I've decided to try gnome-classic instead. It's a pity, because I really wanted to fall back in love with Ubuntu. I can't believe they didn't make it configurable to switch which side a bloody launcher is on. Sure, have your defaults, but make them configurable.
I was using Ubuntu on an X220 as my development machine for a while, with Ubuntu 11.04. It was extremely unstable -- the machine would freeze frequently when unplugging the DisplayPort cable, or even right in the middle of working. That along with a host of small bugs and annoyances (invisible desktop space on the smaller display in dual-display mode -- a longstanding issue in X apparently) eventually drove me back to using a Mac.
On the X220, 12.04 has run perfectly. On the X120e however, which also ran Fedora 16 (KDE) previously, I have to admit that 12.04 was sluggish. I haven't narrowed down the problem - but I feel it might have something to do with graphics performance -- which feels strange, since I always historically associated KDE with sluggish performance due to graphics, not Gnome.
I had some problems with the trackpad in 11.10 (I use the nub, mostly).
12.04 has been nothing but rock solid the entire way. Everything including the above that you said is a problem. Sorry that I can't commiserate, but basically, the X220 + 12.04 are the near perfect setup I've wished for quite some time*
*only thing I would like is a higher resolution screen on the X220.
Gnome 3 fallback is essentially Gnome 2.x all over again, so I'm pretty happy with the results.
Otherwise I haven't run into any problems so far...