I held back because XP worked great. I knew how to use it, used it for years, the graphics were decent, the software worked with no problem, there was tons of software that worked well. Also, I did have an older system, and support under Win 7 for the older components were an issue. I knew it would mean replacing my cam. A huge stumbling block was dealing with all my files. My hard drive was nearly full. Despite having a backup drive, there are still logistics, making sure firefox is backed up, do I have passwords for all my other programs like Skype... nothing was a huge deal breaker, but everything together just outweighed the benefits and by a lot.
Finally I found my games just weren't working well. I had made some hardware upgrades that would allow me to take advantage of Win 7 features. I had a few reinstalls to do that kind of pushed me over the edge. Might as well do the whole thing right then.
Now that I have it, 7 is great. I worried about it taking up more resources, but it uses them so much better it feels like my system runs much better with the new OS than with XP. But for home users there are a lot of reasons to hold out if you already have a decent enough system.