Downloading trial version now.
Table of features compared to previous versions here
An interesting new feature is an exposure merge feature - but as with all these, the success of the tool comes down to how well it does realignment. Wonder if it is only for simple dynamic range optimisation or can it do all out HDR too?
The most curious feature is a scene resize/composition feature. If it is what I think it is, it's certainly interesting. When you resize, instead of simple scaling, selected parts of the scene are dropped, keeping features the same size and reducing any space between them.
Are these already in CS4 or earlier? If so, is that how they work?