The first reviews of the 2013 MacBook Air models are beginning to come out and, aside from new CPUs and a new SSD architecture, the biggest new feature is a dramatic increase in claimed battery life.
Apple has increased the battery capacity of the 13" MacBook Air from a 7.3V 6700mAh unit to a 7.6V 7150mAh battery. As a result, the claimed battery life of the 13" model has increased from 7 to 12 hours. In its review, Engadget found the 13" MBA achieved 12 hours and 51 minutes on a charge under their standard battery test.
Engadget:
Laptop Magazine's test unit achieved 10 hours and 53 minutes on a home Wi-Fi connection suggesting that, while mileage may vary, Apple's claims appear to be largely legitimate.
A review from Forbes found that the battery life would be somewhere between 8 and 9 hours under more strenuous use conditions. Competing 13" notebooks don't come close to reaching 12 hours of battery life without external batteries.
Apple says OS X Mavericks, when its released this fall, will include a number of battery-saving software features which could push the battery life of the new Air even further.
Other notes from the review confirm previous reports of significant increases in flash storage read/write. Engadget reported similar numbers for reads and writes to the new PCIe-based SSDs, while also saying boot time has decreased to 12 seconds from 18 seconds on the 2012 models.
Reviews also indicated substantial increases in both CPU and graphics performance on both benchmarks and real world tests. Laptop Magazine found the 13" MacBook Air returned 44.6 fps in a World of Warcraft test on 'good' settings, comparing favorably to similar Windows machines that returned between 30 and 33 fps in a similar setup.
Article Link: 13" MacBook Air Review Roundup: Apple's Battery Claims Appear Accurate, SSD and Graphics Drive Performance Increases
we need it like hmmmm this fall 
