There is a nice review of MacBook Air over at cnn.com:
"And while the MacBook Air's specs are inferior to those found on the cheaper MacBook, they compare more favorably when you look at other ultraportables, where a price premium is always exacted. For instance, both the Sony VAIO TZ150 and Toshiba Portege R500 cost hundreds more than the MacBook Air and feature slower CPUs and half the RAM as the Air."
A bit later:
While most hardware vendors offer a choice of mobile broadband options, Apple continues to offer none, which is disappointing for a system so clearly meant for life away from home and office.
One of the biggest drawbacks of the MacBook Air is the lack of a user-replaceable battery. While most laptops will be obsolete before their batteries wear out, we are sensitive to the desire to occasionally carry an extra battery for extended field use.