Having purchased PSE 6 for the Mac a year or so ago I was expecting a little more from PSE 8. hence the 3 stars, had it been more than a service pack upgrade with just a handful of new features, some of which can be replicated with a little extra work without using the menu option it would have scored it as 4 or 5.
The interface and been modified slightly with the undo arrows being more to the top right of the screen from the top left (Note not in the right place for most right-handed users). A few new features have been added, which in my mind do not justify the 6 to 8 revision. On my 2.4Ghz Unibody MacBook although its slightly faster in loading, its very slower in operation. Not at all happy with the levels window now being in the right-hand pane and not free floating as in 6. And integration with iPhoto is not 100%, click to edit can be set to load PSE, but saving back does not always appear to work in modifying the iPhoto thumbnail, (but that was the same in 6).
Not a bad price, and if your moving up from a version lower than 6 I would say work the purchase, but if you have PSE 6 I don't think its worth the upgrade. Like but most software houses Adobe seems to issue annual revisions (needed or not, the Mac skipped PSE 7 and the changes are very slight, for Windows users I would say if you have PSE 7 don't purchase.