I have a Spyder2 - I don't think it's 'express' or 'Pro' - I think they split those out later. I believe, but could easily be wrong, that the hardware's the same and it's just a question of different software packages.
Anyway, mine works and I'm happy with it. I use it on LCDs now, CRTs in the past. I do gather that the more expensive units will do better on some theoretical level with extreme highlight and shadow values, but at the level of "I send something to the lab and it looks like what's on my screen" I'd say things are just peachy now, and they sure weren't before I got it.
Stated another way, better a cheap hardware calibration then none at all, that's for sure.