I'm running it on two machines here, and at two customers' sites for client workstations.
The customers use Symantec AntiVirus (both NAV and SAV Corporate), and a variety of applications including Office, Internet Explorer, and one big SQL Server 2000-based application. They also use Quickbooks 2004, Adobe applications, and such.
So far, my experience has been that if you've had massive amounts of spyware, you're probably not going to like the transition too well.
If your hardware vendor is Compaq/HP, you'll also want to be careful, as their customized installs on their Pavilions and Presarios don't take to service packs too well. Yes, my customers have somewhat customized images, and if they're OEM images, are usually the Dell Optiplex images (which are generally very stable).
Otherwise, the only issues I've seen have been with:
1. Customers attempting to use Microsoft Exchange 5.5's Outlook Web Access, because the pop up blocker is enabled by default. This breaks the Reply function, and Firefox has the same behavior
.
2. Customers attempting to install ActiveX controls in IE, because it makes you confirm the add-in step.
3. You can still get spyware from the less-scrupulous shareware authors who enclose spyware with their applications (like the P2P vendors).
4. One enterprise fax application does not work.
Otherwise, everything else works, and the firewall now comes up before the network cards are initialized. That, and the machines haven't had driver issues. People can still connect to file shares and to SQL Server.
Wireless works 100% better. I highly recommend SP2 to wireless users if only for the new, actually usable, control panel.
It still beats Windows NT 4.0 Service Packs 4 and 6. At least this time they didn't mess up the password store or file system
.
If you're a home user, and you're not using Outlook Express, it's worth it.
Mitch