I had a brief look at this lens yesterday in a camera store. One thing I found surprising is that it's bigger and fatter than the 24/28 f/2.8 IS. I shouldn't have been surprised really, since its front diameter is 67mm vs 58mm. It seems solid and well built though I didn't get my hands on it. Maybe next time I'll ask them if I can play with it! (I don't speak Japanese all that well so wasn't bold enough that time).
And now this new rumor of a 35L II? 35 must be the new 50!