The rev B MBA is my primary computer. I have the 1.86 GHz with SSD, and it is faster than my unibody MB 2.4 GHz, w 7200rpm HDD, and 4 GB RAM... also faster than my MBP v2,2 2.33 GHz, 7200rpm HDD, and 4 GB RAM.
The SSD makes it incredibly fast for common tasks like startup, application opening, large file opening, and etc. For the normal, non pro apps, it is extremely fast.
In addition, I use the 24" ACD as a docking station. The rev B MBA becomes an instant desktop driving the beautiful 24" ACD, also with built in power, USB hub, camera, speakers, and using wireless KB and Mouse is nice too. When at desk, I feel I am working on a genuine desktop. Having all of the power is great with the rev B MBA.
Last thing, it has less space, so I use an AirPort Extreme Base Station with USB printer and attached Backup Drive. That really helps. I am looking forward to using the remote access via Mobile Me to connect to my AEBS drive remotely from other networks.
I say go for it. The rev B MBA is super portable. At the same time, the 45 NM Penryn CPU with 6 MB L2 Cache is speedy/powerful, the Nvidia graphics w/Mini Display Port can power a 30" ACD, and the SATA SSD makes the small portable laptop a powerhouse for common computing tasks.
Best wishes.