I had never worn a health shoe with the rocker sole, so this took a short adjustment phase.  I even noticed that my legs were tired after wearing all day during the first week. So I figure they must have some toning advantage.  After the first week, I had become accustomed to them and no longer experienced the "tired leg" feel.  They do seem to run a little large - not so much in length, but in the over-all "roominess" of the shoe.  I noticed that in some of the other reviews that adding an insert helped this, so I purchased an inexpensive pair of arch support inserts to try out and that did help immensely.  The right shoe still doesn't seem to fit as nicely as the left.  I would probably not purchase another pair of these, although they are wearable and I'm sure I'm getting some toning in my legs, but the shoe is just not as comfortable as I would like.