I think there is a lot to be said for the improvements to Entourage and I think the long list of things listed by Andy are of great merit...they have made the product usable in an office setting on a daily basis -by the majority of people.
However, I still think it is amusing that Microsoft went from supporting Exchange server via Outlook (OS 9) to releasing a product that did not support Exchange when Entourage was released. Our Mac users didn't understand (along with the entire MS Office for Mac community) why in the world Microsoft would go backwards. Say what you want about building a product from scratch (as I am sure you had to do with OS X), but it is still a laughable situation.
I've been very happy with the changes -although they take an ungodly amount of time to roll out. Yet with 2008, categories still do not sync (nor tasks)? I thought 2008 would be the end-all-be-all. I guessed wrong.
I still use it and I still recommend Office 2008 to anyone I know, however, I think the problem is that the development model was flawed from the first release.
--- For those that may be trying to sync categories, I noticed that some are coming across after SP1, but they are not accurate (meaning, if you select multiple, it comes into Outlook as one large category). My guess is that a fix for this (along with opening files correctly) is on it's way.