I have had my new 11 inch MacBook Air for a couple of weeks and am happy with it so far.  The battery is easily making over 5 hours use.  The portability is also helpful and I used it for the first time last night a DC Big Data meetup (I recommend that group if you are into "big data" management/analysis).  I expect to be using it this weekend for more serious Eclipse/Java type development and test and will post again soon with a few more practical details on that level of use.