Over the long weekend I decided to upgrade to SP1 and this is how it went for me so far.
I installed SP 1 on my central primary site server. Got a couple "errors" in the setup log and the MP was getting error 500. Reran the setup, all items installed okay except the MP. I played with the MP for a couple days, uninstallind and reinstalling it. Checked DCOM and the SPN's and finally reset the computer account in AD. It finally started working.
Upgraded all my child primary sites with no trouble at all.
Next I will upgrade all the secondry sites then my clients.
Looking forward to R2!