As a triathlete, the t3c works perfectly for me. Although it was a little tricky to figure out at first (the directions are poor) i soon discovered how to view previous data. The "training effect" feature is by far the most helpful, allowing me to reach my goal and knowing how hard I need to train. I also purchased the road bike pod so I can get my mileage and speeds.
This is an attractive watch with potentially nice features. It not only has a heart rate monitor with something Suunto calls training effect, which is a useful concept for an athlete such as myself because it allows comparison of effort level from one workout to the next. The watch also supposedly has the capacity for expansion for a GPS unit which would allow calculation of speed and distance, plus downloading of workouts to the computer. Unfortunately, I never got that far. First of all, the watch, which is very attractive, is less bulky than other GPS watches I have tried and own. Sadly, the watch did not work properly. I found the buttons somewhat confusing but once I learned how to use them, they started to malfunction. It didn't take long for this to happen, only two weeks. Also, for whatever reason, the buttons were hard to press while running. It doesn't look like they should be, because they are fairly large, but they were. The malfunction that I experienced was that the the heart rate stopped showing up on the face of the watch, and the button used to scroll to the heart rate would no longer work. Also the Stop watch feature would not "stop" which was frustrating when you wanted an accurate time. Perhaps the watch I received was a "lemon", however, for the expensive price tag, it should not have malfunctioned the way it did.
I bike and run and use this HRM probably 5 times a week and am very happy with it. the build quality isn't the best but it is the most attractive HRM I've found, which doesn't mean much.