I avoided it like the plague. You may want to give it a shot.
I use iMovie 09 all the time.
iMovie 09 is wonderful to edit a 5 minute video to share on youtube, but it lacks features that are needed for longer projects or if you want to make a DVD of your movie.
iMovie 09 uses 'single field processing' meaning every other horizontal line of the video is thrown out, which reduces the sharpness of the footage. iMovie 06 uses ALL of the image to form the video.
iMovie 06 and iDVD is a "lossless" combination.
iMovie 09 is a wonderful program assuming that you're using it for what it was designed to do, assemble videos to share on the Internet.