I owe several jobs to the inadequacy of Apple iMovie, so it's probably good to track its progress. The latest version (guided tour here) seems to be 2 steps forward and 2 steps back, adding slick features (like clickless scrubbing) but at a high price in waiting time for thumbnail rendering and removed features.
I'm not sure if this will finally push the skilled low end to Final Cut Express, but experienced editors are weighing-in. The Edit Blog seems to like Working with iMovie 08, and Splice Here asks How much editing does the average person need?
David Pogue also weighed in with 'thumbs way down' in his NYT article Apple Takes a Step Back With iMovie ’08.
Update: Splice Here has more thoughts on iMovie in iMovie as a Gateway Drug, and notes a MacBreak Weekly podcast. He also notes a very important Apple secret weapon: “Export to Final Cut Pro” -- but does Avid hear?
Update 2: FrshDV notes a positive review, Why iMovie ‘08 Matters.