I didn't get to play with the betas that much for this product, so this was my first real exposure. I decided to install it on a couple of virtual servers I have running on my main development server. In both cases, I can access the virtual servers either through the Virtual Server Administration web pages or through Remote Desktop. Installation on both servers worked without flaw, but I noticed it locked down nearly every port, including Remote Desktop! The one port it leaves open is the port used by the Security Configuration Wizard (which you still have to manually install). So, if you are installing this over a Remote Desktop connection, you may find after you reboot that you are no longer able to access your machine. I am sure there must be a work around for this, but I don't know what it is at the moment.
One nice feature is that when the Service Pack has been installed, all the previous hotfixes are removed from the "Add/Remove" window (since SP1 rolls them all in, the "uninstall" operations for hotfixes are no longer needed, but I don't remember other Service Packs removing those previous ones for you like this one did).
I started to run the SCW, but backed off as I want to put a couple of other bits of software on the servers before locking it down completely. So far, except for the Remote Desktop issue, I am very impressed.