Hey guys, quick background: I'm a competitive college athlete that runs and lifts weights 5-7 days a week. I've worn these shoes for the past two years and I just got back from completing my first Tough Mudder event yesterday with these shoes. After two years, I have to say - these shoes are AMAZING. They're extremely light, comfortable, and have helped me adapt to a barefoot running. In summary:

Pro:
+Light
+Comfortable
+Lasts a long time

Cons:
-Expect friction burns on the pinky toes in longer runs (i get them during my half-marathon runs...but this is solved by wearing socks)
-Grip (I noticed some traction issues in about the last few months...then again i've been using these bad boys for a long, long time so it's bound to happen at one point or another. Despite everything, still had enough grip in them to power me through those damned hills during Tough Mudder!)

If you're in doubt, don't think about it and just buy these. You won't regret it ;)