It’s better than using a regular trainer (marginally). However, the power output and pedal scan are VERY helpful IMO. I’ve done all kinds of fitting adjustments on one and have been able to get more dialed in than I could have gotten from just a regular bike shop fitting. It’s also great for doing test sets and for being extra anal with intervals.
You may want to call around to some local bike shops to see if they offer computrainer demos or group workouts/races (usually the group workouts have a small fee). It’s a great way to see for yourself if you like them.
My view: computrainers are definitely more fun and the power feature is very nice. However, I can get the just about the same workout benefit (minus the power data) by using my fluid trainer and some good spinervals DVDs–for about 1/4 of the price.
I love my computrainer, and don’t forget the new software that will be coming out in December that has the actual video of the courses. I used to have the fluid 2, but i found that it didnt provide enough resistance, the computrainer has the load generator which really challenges me.