Ars reviews the mid-2011 MacBook Air

Pros:
Size and weight
Good screen
Excellent backlit keyboard
Long maximum battery life
CPU performance on par with last year's MacBook Pros
Thunderbolt port
Network recovery

Cons:
No Kensington slot
Network options are a bottleneck for local file transfers
Hard to get the best battery performance in real-world use
Software support for higher resolution display incomplete
iLife software tied to your account, can't be resold with the machine
Network recovery