Actually, FCP 3 is more crash-prone. Also, the timeline video (not slug) is pretty messed up - dropped frames, odd colors, etc. I'm guessing this has something to do with the video framework. I run a 733 Digital Audio G4 w/ a GeForce 2MX.
On a plus, you can now export to MPEG-4 and play it with Quicktime 6 - the compression is a little better than Sorenson 3 (depending on certain variables, of course).
It's still very usable, just quirky.
Brad