I have used the shoes today for the first time. I went for a 15 Km run. The shoes were uncomfortable initially but they adapted the foot during my run. I think the break-in was done only in the first run. A good running shoe makes a difference in your running efficiency, Foot health, and comfort. You can go for it if you are a beginner in running like me. Don't buy more expensive shoes than this. First give yourself a taste of Nike run, then eventually you will be able to upgrade accordingly....