From what I've read, it runs fine on the iBook. It scales back the coreimage, so you won't see the ripple effect when you drop a widget on your desktop. I've read reports that is faster on the G3 than Panther was.
Hopefully, it'll run like poo after eating dicey extra spicy Vietnamese food.
Sorry, couldn't resist.
I'm curious too. But so far, everything people have posted seems in line with the past history that says macs run 5-10% faster after an OS upgrade.... Can't wait till I get my copy!
I have the exact same computer as you spec wise, so I think I'm qualified to say that Tiger will run great on your machine. The whole gui seems faster and more fluid than Panther. Window resizing, and selection in the finder are greatly improved. A major pet peeve of mine was, when viewing a folder full of image thumbnails in Panther, my machine would take forever to display all of them. In Tiger, i can have a folder full of hundreds of images with all my thumbnails showing within seconds.
I currently have 7 dashboard widgets running, that are assigned to a screen corner. There is no noticeable lag whatsoever. You wont get the "whiz-bang" ripple effect but to me that's incidental. There is a very slight lag in the spotlight search window while conducting a query, while it searches for image previews and application icons. This is negligible b/c by the time it conducts it's search all previews are finished. All in all I am already addicted to Tiger, and find myself wondering how I ever lived without Spotlight!