I tested out my new MBA on battery for the first time tonight. It's pretty incredible. Streaming Aereo in HD over wifi the whole time, coding and doing other tasks on normal brightness. I went 4.5 hours before reaching the 50% mark.
I expect that the reason the Air was the first Mac to be updated to Haswell is that Apple feels the need for its engineers to be ready to respond to Surface Pro and other Intel-Core Windows-8 tablets and convertibles.
Oh absolutely. Have you tried the Chromebook Pixel from Google?