I bought a pair of these in white/silver, and so far I am very happy with them!!  Not only are they very comfortable, but they obviously do what they are advertised to do.  I can tell that my currently-targeted muscles are my quads and calves.  Walking on an incline or going up stairs will definitely target the muscles in the 'gluteus maximus' as well!

Additionally, the balance point of these shoes will give you an idea as to where you most distribute your weight.  Obviously my WiiFit does not lie, because I notice that I am putting more weight on my right leg than my left.  Hopefully being conscientious of how I distribute my weight on these shoes will change that.

I would recommend these shoes to anyone :)