I got the high-end 13", with the i7, 8GB RAM, but the 250GB SSD, and I haven't looked back
It is faster than my MacBook Pro from 2010, which was also the i7 version, with upgraded RAM and SSD.
I might actually sell the MBP, which is something I have never done before (I still have my 1st Gen. MBA), that's how happy I am about the new MBA. Only thing which is nagging me a bit; it does not have the Retina screen, which will probably be in the next upgrade, and I almost forgot, it only has one Thunderbolt port, and until there is a Thunderbolt hub available, I have a challenge at work; I use the Thunderbolt for the external display, but sometimes also need the port for the Ethernet dongle (bad WiFi).