Pretty much every review I’ve seen by someone who has read all of the specs can be summed up as: “this would be a fantastic machine for someone else”. The deal-breaker for me (and I was already lukewarm on the concept) was the lack of ethernet, which means that the spiffy-keen “use the DVD drive on any networked Mac or PC when you need one” feature is crippled by the performance of your wireless network or Apple’s optional USB 10/100 dongle. Suddenly it doesn’t seem so spiffy. Also, if you spring for the outboard optical drive, it ties up your only USB port, and they don’t mention it including a hub.

I can’t see very many people adopting it as a primary machine, which means syncing configurations and data to another Mac. .Mac sync sucked horribly for the entire lifetime of Tiger, and I still see occasional outages for .Mac mail. They claim to have put a lot of work into it for Leopard, but if the Air is really a secondary machine, then they need to add direct sync between Macs as a solid OS feature.

I think the real accomplishment of the Air will turn out to be improving the quality of lightweight PC laptops and tablets running Windows Vista. I expect to see the first round of them in about three months.