I had a lot of the same concerns as everyone else with this shoe when I tried them on. The front pinched my toes, there seemed to be little or no lateral support and the rigidity of the sole (or lack of) made me second guess my purchase. I decided to give them a try anyways; worse-case scenario I would use them as warm weather fly fishing shoes.
By no means is this a comprehensive test, but I thought I would pass along my experiences. I received the shoes 3 days ago and so far I've logged a little over 25 miles on them. My running trails include steep inclines/descents over loose rock, hard packed interlaced with large flat rock surfaces, intermittent stream crossings and a limited amount of 1960's era macadam. On both days the trails were dry and I have not experienced mud nor grass.
The toe pinching disappeared within the first mile and by the fifth mile the shoe fit like a glove. Contrary to my initial impressions, I actually enjoyed the lack of rigidity in the sole and heel to toe transfer felt very natural. The weight of the shoe may have contributed to a more natural feeling as well. The shoes traction was excellent; even on loose dirt inclines I had zero slippage. The shoes drainage was what I expected with so much mesh and all water was expelled from the shoe shortly after exiting the stream.
The lack of rigidity did create some problems. With the softer sole you really do need to watch your foot placement – pointy rocks will cause you pain. The sole issue also put more strain on my foot then my other trail shoes when quick stepping up rocky inclines. The colors – need I say more.
I'm still undecided about the lateral support issue. I felt the shoe handled well and I had only a few ankle instability issues. I am currently rehabbing my right ankle and feel my input on this issue may be askew.
All in all I love the shoe. For me, the final fit and more natural feel are worth having to be more careful about foot placement.
As for Matthew's concern, if your are planning on keeping the shoe, I would not use these in rocky terrain until you have completely healed.
As to fit, I wear the same as my road shoe (Asics Nimbus).