I'm recently converted to my 1st Mac, a 24 inch Imac. It's a beautiful machine and I'm loving it.
Now I'm not saying it is absolute perfection, but on the whole it's been a very pleasant experience. At this stage, it's only been four months I can't see my self going back to a Windows machine. I'll need to buy a second computer in the next 12 months and it is definitely going to be a Mac of some sort.
I'd say the main thing is to expect a bit of frustration while you get used to different was of working and learn your way around the OS. Get it when you don't have urgent stuff to do and it's not too painful.