I was in the early crowd of MacBook Air buyers and for the first month I absolutely loved it. I originally bought the Air after a trip to Japan where I lugged around the 15 inch MacBook Pro on all the trains and subways until my back couldn't take it. The Air's weight and form factor are near-perfect if you commute or travel and when I was in the office a USB hub and power supply were always available.
However, once I started hitting the road, the MacBook Air disappointed on many occasions. Hands down the biggest issue is the terrible battery life. Despite trying every setting, even custom configurations, I was never able to get more than two and one-half hours of battery and in some cases couldn't get more than one hour. I'm not going to dwell on the performance except to say it was weak. I knew what I was getting into with a low-horsepower processor and limited (2GB) memory.
Battery life is embarrassingly bad
My first really annoying experience was when I rented Lars and the Real Girl from iTunes and tried to watch it flying from SFO-NYC. However, watching it in full-screen mode made the machine die in about 45 minutes. The movie wasn't great so I figured I would wait until I got to NYC and charge the machine. But, by the time I got there my 24 hours had elapsed and I couldn't finish it.
I had a similar experience flying from San Diego to SFO trying to calm my crazed infant with videos. The damn Air died after 45 minutes of full screen Elmo, which was just ridiculous for everyone around us.
Lack of ports is more problematic than you think
One USB port is just not enough, especially when you are forced to use wired ethernet. This happened to me on the NYC trip when the Westin didn't offer wi-fi in rooms. I had to go to the 24 hour Apple store to buy another USB Ethernet dongle or sit in the lobby to use the internet.
With the MacBook Pro I could usually just charge the BB directly via USB and not have to carry another charger. The Air offered no such luxury, sometimes because it just didn't work and other times because I needed the USB port for something else. On that same NYC trip I had to run to a Verizon store in between meetings to buy yet another Blackberry charger.
Did I mention that the battery life is terrible?
A big selling point for the Air and other lightweight netbooks is that you can carry them around. Except with the Air's terrible battery life I had to take my whole laptop bag everywhere so I would have the power cord.
I really liked the keyboard, it was bouncy and I could type really fast. But I couldn't take the machine to conferences to blog or take notes unless I wanted to lug all my gear. And considering how difficult it is to get power (and often wi-fi) at most events, this became annoying very quickly.
I had a lot of other issues
Lest you think I came to this discussion on a whim, I documented my experiences fairly well. I'm sure I'll get flamed for this post, but the MacBook Air is easily the most expensive, worst value for the dollar computer I have ever owned--and I have a Cube sitting in a closet somewhere.
Previous MacBook Air posts:
Why is Spotlight using 98% of my MacBook Air CPU?
My MacBook Air dies while Google Docs is offline
Month 4 verdict for MacBook Air: OK, but not great
MacBook Air battery dying within 2 hours--any advice?
MacBook Air major annoyance--when sleep doesn't mean sleep
MacBook Air one month check (Verdict: It's great)