No problems whatsoever with SP2 for me.
For people that are having issues, it's well known that 95% of SP2 problems are caused by the new Windows Firewall, which needs to be configured for a lot of older programs to work. Software developers have had about 6 months notice from Microsoft about the effects of SP2, and the majority have done nothing, or are only just sending out updates when it's too late (*cough* Symantec *cough*). If you install SP2, update all of your drivers and download the latest versions of all your software.
Steve.