I've been training with power (by watts) on my Computrainer since I signed up with Endurance Nation in October. Now that teaches you how to ride a bike! I've drunk the Kool Aid, and am totally convinced of the effectiveness of training and racing with power. Once you understand it and experience it, there is no going back. It's a total paradigm shift, and a look into how the pros train and race.
Since I am now a watt-aholic, I just ordered myself a brand new Power Tap Pro. It comes will be here in within two weeks. I can't wait! I'll post ride and progress data as I go along in my training, particularly improvements at functional threshold power. With any luck I can be back riding outside by the time the Power Taps arrive. Been stuck in the bike dungeon--I mean basement--since October, and I am anxious to get back outside!