My Powertap taught me that most of my training was at a lower intensity than it needed to be to prepare me for what I want to be good at. It also taught me that my recovery rides were a little too hard to really be recovery rides. It also taught me that my pacing was not up to much, and i regularly went out too hard too early and suffered later without really knowing why.

Within a month of getting my first power tap, I put in a personal best time on all of my training routes purely becasue I payed close attention to pacing myself better, and that was with minimal data collection. Now I dont ride without the powertap ever and I find the data very useful both for understanding my training load and fatigue and for pacing my best efforts.

Well worth it IME