Generally good, but one problem
Mine has been through the ringer since I've had it - I have it hooked up to an external monitor and bluetooth every day at work, and carry it every day - often through some tough business travel, popping it out on trains, planes and busses. In short, I've beaten the crap out of it.
The only two things that have started to be flaky are:
1) The feet. I've lost one, and one seems like it might fall out soon.
2) The combo drive. Mine has just started this behavior wherein sometimes when you eject a disc (either a CD or DVD), it sounds like it tries to eject, then "reloads" without popping out. I can work around it by sliding a business card into the slot and "helping" the CD out, but the drive is clearly flaky.
While it's still under warranty, I can't deal with being without it for even a few days right now. Hopefully a G5 powerbook will come out b/f the warranty runs out on my iBook G4. If that happens, I'll move, then get it fixed, then sell it on eBay.
Oh, and max out the RAM. You'll be glad you did.