Ryan Block's review of the Mac Air (or just Air) on Engadget is the most thorough I've seen so far. Before this review was available, I instinctively thought that the Air would be a difficult product to decide on...and this write-up seems to confirm this.
The reviewer describes the Air as being a tough call, being hard to justify its price with all its compromises, but a technical wonder nevertheless. It's doubtful if the Air will be a primary machine for users, as it's not going to replace users' main workhorse. I haven't seen the Air at the Apple store yet, but I sense that it's an 'into the future' machine... Apple is anticipating what mobile wireless computing will be in a few years, and the Air is it.
I'd love nothing better that an ultra-light from Apple such as this one...saving a few pounds from my hand luggage when traveling would be wonderful. However, I will wait for further reviews before getting all excited.
Engadget's Mac Air Review