Althought I don't use iMovie on a G3 (iMac 15" G4), I'm seriously disliking the way iMovie now works... case and point(s):
1) Slower editing. I've noticed that the simple act of de-selecting a clip from the work area takes at least a good 2 seconds. Very frustrating when you're "in the zone".
2) Titles cannot be "commited" anymore, which makes it difficult to chop, paste over and alter them with other clips. (Most often, they'll magically create a duplicate clip that is the full original, rather than the shortened edited version you were trying to create.
3) Longer load time. For some reason iMovie now takes a great deal longer to get up and running (either with a fresh project, or a new one).
Aside from that, if Apple could work to improve these little anomalies I'd be pretty happy. I like the fact that you can custom edit the levels of audio now at various key points. It looks like iMovie will be eventually growing into the Adobe Premiere user-base... but it will take some time.
Aside from that, I recently just purchased Apple FinalCut Express... I haven't had a chance to use it yet -- at least not until get some projects out of the way. But, Apple has a nifty little how-to series in Quicktime to help you get up to snuff and started with FCExpress.
Get Started With FinalCut Express
