Well, once you've been through the first book there's not much to do. The potion making thing is clunky and on my system is a bit slow and jerky. Actually, the whole site is slow and jerky for me, even though there's no sound.
A lot of it is just a brief sentence about the chapter, then a picture with a small bit of animation that takes ages to load, then you look around for something to click. Only some of the chapters actually have anything interesting and even then it's not the interactive 'experience' that was hyped.
The extra bits of info that you can find are the sort JKR used to give out on her personal website, and at least there you had puzzles to solve that were fun (anyone remember the wizard gardening radio show?)
Yes I want puzzles (I'm a Ravenclaw) but I was also hoping for more background info on secondary characters, or places that aren't explored much (or at all) in the books. At least the background image of the Ravenclaw common room is nice.