We’ve just bought the 11″ /128gb job for my wife. A lot nicer all round than my white macbook. Obvious limitations are that unless you buy one of the new Apple displays you’ll need an adaptor to run an external monitor, and that it’s extremely useful to have wireless access to additional storage, with no ethernet, 2usb ports and limited onboard storage. Do spec it as highly as you need at purchase too, there’s no user upgradable parts. I’m not even sure whether Apple will retrospectively upgrade drives etc.
A real luxury item but I’m glad that we waited for these to appear rather than buying the small macbook pro which was going to be the original choice.
Oh, and side by side, I reckon the portability of the 11″ is more desirable than the increased resolution of the 13″.