Not really annoying at all, at least to me
The Air has 2GB of RAM standard. And for most of us, that's enough. So I'm not traumatized by the fact there's no way to increase its capacity.
Potentially crippling omission
If Steve Jobs ran the world, there'd apparently be no such thing as a battery you could remove-or at least that's what you might suspect given that the Air is joining all iPods and the iPhone as Apple Products That Don't Have Batteries You Can Take Out.
For many people, I think, that'll be a deal breaker. If the Air really gets five hours on a charge, it helps--that's enough for a cross-country flight. But I've bought a second battery for most of the notebooks I've ever owned, and used it from time to time. And I'd worry about the Air's battery losing its charge over time and wanting to be replaced, and that being a hassle. (Big question: Will Apple Stores be able to do battery swaps quickly, on site?)
(And random related thought: If all airlines did what Virgin America for one has done and put power jacks at every seat, would that make most of us a lot less obssessive about needing to be able to remove a laptop's battery?)
I love small, light notebooks. I admire great industrial design and clever engineering. And I've carried Mac portables as my primary notebooks for about four years now. So in theory, I should be a candidate to become a MacBook Air owner.
Would I buy one for myself, based on what we know about the machine?
No-for two main reasons. Reason one is the hard drive. Eighty gigs is just too small; it would severely limit my ability to enjoy using the Air. If Apple announces a 160GB Air, that concern would disappear instantly. But reason two is the fixed battery, and I doubt we'll see an Air anytime soon that lets you remove the battery.
But I'll sure be watching this machine closely. I can't quite tell whether it's likely to be an influential hit or a Cube-like dead end...but it'll be fun to find out.