I had multiple version of the 13 and 14 and loved them. The 15 is just not working for me. I don't feel I am getting the pronation control that I expect from the GTS. The tongue of the shoe seems massive. And to top it all off, I have a huge blister on my heel! I've been running in GTS's for two years and have never once gotten a blister before. I'm so bummed because now I need to go back to a running store and find a shoe that actually fits.