I have a 12" G4 PowerBook, and I love it! It's the most usable machine I've owned (after my Amigas).
Stuff on the Mac is so easy that I find myself doing stuff I've either not done for years or never done - like making videos.
iMovie is really easy to use. But, it's also slow - if you use the wrong video formats. I learned this the hard way - I put up with 20 minute imports of a few minutes of video for ages, but by accident found that if you import a video in the same format as what you asked iMovie to create the video in, it's instant. Obvious, when you know about it... This means that I convert on my Linux box first (literally seconds for 300MB of film) then import that into iMovie.
On my Mac, it is however buggy. I can't add transitions. The transition doesn't render. And if I'm really lucky, iMovie crashes. I suspect this is my install. Sadly iMovie 08 doesn't support the G4 so there's no upgrade path, which means it'll have to wait until I get my new Mac laptop (which I've been promising myself for a long time now).
Strangely iMovie is the only app I get along with in the iLife pack. iPhoto is useless to me for example.
iWork I'm quite impressed with, but then Microsoft Office 2004 for the Mac is just excellent, in terms of speed, user interface and usability - suprising since I consider Office 2003 and 2007 on Windows the complete opposite!
