Win7SP1 came up as a Windows automatic update last night so I installed it and have done three restarts and one more "check for updates" now to insure it has settled down. For major updates it is a good idea to watch the CPU Usage History graph in the Performance Tab of Task Manager so you know when all processes and services are fully loaded. I keep a shortcut to C:\Windows\SysWOW64\taskmgr.exe in the Start Menu>All Programs>Startup Folder so it automatically opens whenever Windows restarts.
Windows7 Home Premium x64 took about 3 min 7 secs to fully load. It appears SP1 has added about a minute to that as the CPU Usage History graph doesn't flatline for 4 min 2 secs. I load 70 processes, but that will vary for each user based on the software installed.
It took a while to find the release notes and a list of the 796 hotfixes and security updates included in SP1. They can be downloaded at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=61924cea-83fe-46e9-96d8-027ae59ddc11&displaylang=en
So far everything seems to be working great.