You pay a premium for the operating system. Whether you think it's worth it or not is the deciding factor.
I haven't owned a Windows computer since I got a Quicksilver G4 tower in 2001 or 2. OS X is efficient and trouble free, I never feel like I'm fighting against it to do anything. I could probably go back to Windows if I figured out how to strip a computer of all the bullshit manufacturers add on (media center stuff) and how to make it less flashy, but I'd rather stick to OS X.
As far as the computers themselves - they're perfectly fine. No better or worse than any other high-end laptop IMO (ie Lenovo or the like), some nice features (like the new trackpad). I'm not completely sold on the glossy screens (really, Apple, you build yourself around appealing to 'creatives' and then fuck them?) but not as opposed as I was initially.
The new keyboard is nice, though I wish the 17" had a real number pad instead of a ton of dead space.
If you're going to buy one, get the base 15", put in your own memory and a 320GB 7200RPM drive ($90 from NewEgg), don't pay Apple premiums.