People may complain like mad, but the fact is it is a stable, good operating system. It recovers from errors far more effectively than XP does (if explorer happens to crash, i get everything back in my various trays and in mere moments, versus XP were things may not appear again until the next reboot). What people constantly complain about is more the fault of driver makers. Vista tries to force software makers to reduce, if not eliminate, their need for elevated permissions as a measure of increasing security. I run Vista Home Prem. on a HP laptop, core 2 duo (originally 1 gig ram, now 2), with a medium sized hdd (160 gb) and integrated intel graphics, without issue. i use office xp without much issue (occasional graphic artifacts). I love it. Granted xp was great, but Vista is wonderful. it can run on a lower end pc, just lower what it's trying to do. disable aero, decrease some of the effects, etc.
In the end, I personally consider it to be the best MS OS out. Friends of mine agree. One of whom only switched back to XP because there was a driver he needed for work that didn't exist in x64 form. I've been told by friends that run it in x64 that x86 emulation, when needed, works seamlessly.
SP1 just makes it better. File transfers/copying has been greatly improved. I'm sure there were some other fixes incorporated with it, but none as outstanding as the file transfers. People may complain about SP1 crashing their system, forcing a reinstall, but remember that XP SP2 did the same thing when it first came out.