Honestly, I can’t make up my mind.
The compromises in processing power seem significant – even the speediest CPU on the top-of-line 13″ model is a mere 2.13 GHz Core2Duo chip, i.e. 20% slower than the 2.5 running my old MBP, and I am assuming Lion will be at least 20% more cycle-hungry (perhaps more) than two steps back Leopard.
And while they gave it two (wow!) USB ports, it still doesn’t have a dock.
A reasonably configured machine including a display (can’t really work on 13″ except on a plane) goes for 3,000 euros which is roughly the price of a much more powerful MBP (2.8GHz Core i5 + 8GB RAM).
Trading power for weight? hmmmm….