Downloaded and installed XP SP2 today. It took about 3 hours to download from MSDN and install. The new wireless network GUI is nice. The security center is cool. I installed one of the recommended anti-virus applications (CA's EZ Trust) It tried to take over the firewall and it had all these popups and it was just annoying so I uninstalled it. The new windows update is out too. Nothing really different, new interface and some links for network admins. When you install an update from Windows Update and select "Restart computer later", it puts a little icon in the task bar that opens up a dialog box every 5 minutes or so asking to reboot the computer. That's annoying. There is probably a place to turn that off, but I can't find it.
I really didn't have a "need" for SP2. I've never had a virus or "attacks", and I use google's pop-up blocker. Our customers will have this installed on their machines in the next 6 months or so, so I just wanted to make sure there wasn't any surprises.