For those that are interested in some initial impressions, I just got back from the very busy Apple Store at Chadstone, VIC where they had 11" and 13" MBAs on display. I had a good 20 minutes playing around with both and I have to say i'm blown away.
For light duty email, surfing, video watching, iPhoto, Facebook, YouTube etc, these are killer machines.
Looking at the spec sheet you'd think you're in for a pretty ordinary experience but believe me, these does not feel like slow machines at all. In fact, they both leave my 2.53Ghz Late 2008 MBP for dead. Now that is mainly due to the SSD drive (ok, solely) but its amazing how much that makes up for a slower processor in terms of the overall responsiveness of the system. In general, the extra time taken in CPU cycles is MORE than made up for by the blistering speed of the SSD.
As a quick test, I fired up the 1080p version of the Cars 2 trailer on the 11inch and looked at the CPU utiliisation: ~12%. Obviously this is thanks to the hardware acceleration but given that most OSX apps support H264 acceleration, even the 11" will be a cool, stutter-free and very watchable hidef video experience. Unfortunately they didn't have Flash installed so I couldn't check out any video web sites (tsk tsk Apple, you should at least have it installed on your demo machines!) but overall the web surfing experience was brisk and satisfying (probably BECAUSE there was no Flash to slow it down
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All in all, stoked with the 13" purchase although I'm thinking I'd be just as happy with the 11" (well, my Wife would) but its only for around the house so I don't mind the extra bulk too much (not that the 13" is a "bulky" machine at all).
Can't wait for delivery next week!