so, first off, i love wearing these to the gym. it's like you're wearing socks. I could easily wear these all day (and I have). Secondly: by now you have seen people mention the smell. yeah, it's a real thing, At first throwing them in the washing machine did the trick, but not anymore. but it's not a huge deal, except when they stink up my whole car.

but the main problem is hard to explain. so, the bottom is super thin, and it has "pads" in spots where you're foot would meet the ground, for protection. but the problem in that the pads are slightly smaller than the pads of my feet, and the have abrupt edges to them. this isn't noticeable unless you're running. after about a mile or more, I start to feel a very specific pressure point. It took me a while to realize i was actually feeling the edge of the pad through the thin sole. it gives me a blister almost every time.
Vibram has recently gone crazy with their VFF series, and there are so many now i have no idea where to start looking for a solution.