Vista did a bunch of great things... It added BitLocker drive encryption. It added the Snipping Tool for screenshots. It added a newer driver model that end up making drivers far more reliable than on Windows 9x and XP. It required drivers to be signed, which helps a lot with security. It added UAC, which was initially painful but also really helped improve security (no more running every single process with admin permissions). It moved C:\Documents and Settings\ to C:\Users so we didn't have to type that long path any more. And probably a bunch of others I'm forgetting
It was kinda half-baked at the time, but these are all major defining features of Windows. It just took a while for them to become stable.