There is a time and place for every device in your life, including your GPS watch. They can be highly effective training tools but can't replace the fact that you still have to run fast and trust your body to do so!
One of the trends I see is that the harder the athlete tries, and the more important the results, the less satisfied the athlete is, and the worse they run. I call this the “paradox of trying hard to run fast”. Simply put, for motivated and results-driven runners, the recipe that worked in the beginning of season when the stakes were lower is no longer working. Ironically, the more the focus goes into the results, the more the performance continues to decline.