A great minimalist shoe.
Pros
lightweight
can be used without socks
fit like a glove
Cons: not for everyone
These shoes feel like they were made for my feet. I have relatively narrow feet but a wide toe-box. I also have fairly high arches. I do not have any stability problems and have been running in Brooks racing flats for four or five years now.
These are now my favorite hiking shoes because I spend a lot of time in wet and muddy environments. The fact that these fit so tight to my feet means that they don't get sucked off my feet in the mud. The low surface area also reduces the amount of energy you have to exert to take each and every step in mud and water. Spend a day hiking 8 miles in knee-level water in Big Cypress and you will regret having traditional hiking boots. They also dry fairly quickly, compared to most shoes. There is very little material to soak up water, thus very little water to trap and lug around with you all day. I never wear socks with these shoes, preferring the barefoot. I have only once gotten a blister, and that was after a 2 day, 30 mile hike.
I do not like these as much for running, as they are very much a minimalist shoe and take some getting used to. On the trail, I can feel the surface, which makes me feel more connected. Sprinting quietly and lightly over a nice soft bed of pine needles and Everglades peat is a wondrous feeling indeed.
They are also great for obstacle/mud/water crossing races.
Because of the lack of almost all aspects of 'normal' shoes, your feet do get a work-out in these. You'll notice muscles in your feet that you never even knew you had. If you don't build up to using shoes like this, you will hurt yourself. So just take it easy at first.