The only differences in the new 13" and the 2010 Ultimate 13" are the i7 Processor (clocked at a slower frequency), the non-dedicated Intel Integrated 3000 graphics which is sub-par with the 320M (and takes away from your 4GB of RAM), Thunderbolt Port (aren't too many Thunderbolt devices as of now), and the nifty backlit keyboard that you would only use in a dark room or at night.
Everything else on the 2010 models is the same, and some of the specs (such as the graphics card) are even better. Mine has 4GB of RAM and a 256GB SSD, webcam, and 1440x900 resolution (same display) as well.
So basically the three things you would trading up to with the new models are a beefier Sandy Bridge processor, Thunderbolt Port, and a Backlit keyboard (and that is it).
Anyways, congratulations on your purchase and enjoy your new MBA!
Don't forget the bluetooth 4.0