I been running in these for two years now and what a shoe! I still run in my Saucony (hurricane) about 50 percent of the time but the Free's have sort of blown me away. I did do a break in with them such as walk around in the house and use them for a short 10-20 min run warm-up just to acclimate my feet for a couple weeks. I did manage to blister a couple times in the beginning because I felt like I could just keep running(and I did-ouch),but that was also due to the insole rubbing awkwardly on the inside of my fwd-arch. After that its been a plesure to have them as part of my running arsenal. They are very light and flexible which is nice for packing. I'm ready for another purchase of "Free 5.0" or maybe "3-4"! Hope this helps someone!