The near 5 star ratings on this shoe to go along with the $100 price tag are beyond me.  These are $40 shoes with an interesting forefoot stride gimmick to switch up training every now and then, but I won't be buying these again.

Here is my summary:

Usability: 3 Stars
TRAIL ONLY!  I would not hit the pavement/cement with these guys for more than a short distance because you will eventually feel it in the form of pain instead of muscle burn. Once you've gotten tired and you end up using a heal strike, there is certainly nothing to protect you.  I've tried these out in the gym (yes I know they're trail shoes) and they have very poor grip.  The sole is made to last, but with that comes a very hard sole that's not going to do well on ground without its own traction.  I also tried these out in a beach run race and the people with Vibrams 5 fingers were whizzing by as I had basically lost all my traction.

Flat terrain: 4 star.
If the ground is flat, these are just fine.  These shoes will basically force you to run on your toes if you want to run efficiently and on races with flat trail terrain I felt that these were plenty comfortable.  I would recommend for distances of at most 5K because they are easy to clean (use bleach) and they will train your foot differently than most other shoes.

Hill terrain: 1 star
I used these on the tough mudder competition (10 miles), and I would say that these shoes are borderline dangerous if you're looking to hit a trail on a mountain.  Specifically, coming down the mountain you don't realize how much you actually need to use your heals.  Shoes such as New Balance Minimus has some fantastic heal traction that I would prefer, but these basically try to put the traction completely on the forefoot.  The traction however is not in the direction that would prevent slippage down the mountain however. It is in the stride direction.  To me, this is a big DO NOT USE if you are going down steep mountains.