I like it a lot (before this I was using the 17" MBP, which I loved, but the portability factor wasn't so great). Most of my time is spent dealing with linux-based servers, so the BSD underpinnings of OS X really make things like handling SSH keys, console apps, perl debugging while flying, etc. really smooth.
I do miss the larger screen of the MBP and the extra horsepower (I do a fair bit of digital photography, and the MB can't run Aperture), so I'll probably switch back to a 15" MBP soon.
In the ~2years I've been using Mac laptops I've never once longed for Windows in any way. But before this I was using linux as my primary desktop, and before that Solaris, so I've never really been addicted to Windows, although I did have Windows machines in my possession since, well, since Windows was invented (mostly for work or other non-personal use).
The MB (or MBP) with a big external monitor and nice BT mouse and keyboard is really (IMO) a very pleasant overall experience. I encourage you to convert :)
I intend to take that $1K and put it toward an iMac -- that'll give me two Macs and three screens, and the iMac will provide the larger hard drive and improved video performance that I don't have with the Macbook. Plus, when the Macbook is away for its warranty repairs, I get to keep working!
I guess I am pretty convinced that the Mac Book is the way to go, and spending the extra 1000 on a iMac (or Mini) isn't a bad idea.