Very comfortable for running. Fits nicely on the foot. After 2-3 uses, the front air sole "activates" and can give you a strange sensation under the toes, but you get used to it (at first I thought there was a defect, but I read on forums that it is normal and provides extra shock absorption). It has a slightly small fit compared to other Nike models and personally, I would prefer to have gotten a half size larger. The only drawback is the relatively reduced grip on the front part, which does not make it ideal for isometric exercises (slightly slips on planks, bends, etc.).