Another thing to mention about Training Peaks is something outside of the application. They have created a really impressive blog which coincides with the application and includes insightful articles on training, nutrition, coaching and other nerdy sport-based topics which I love.
This is great as it shows that the system is constantly being updated, and helps other people learn how to better the quality of their training, which is what this application is all about.
There are also sometimes articles which showcase data of professional athletes events, so us mere mortals can drool over their numbers and data! Check out Data Analysis: Highlights from the first week of the Vuelta for some pro numbers!