These shoes are well worth the investment. Within one day, I noticed some relief in my lower back & hip, which are often stiff and painful after a day of walking. Other reviewers have complained of trouble with the velcro straps being short or coming undone, but I did not have this problem. Perhaps they fit me well because I am small-boned and have a relatively low arch. (I am 5'5 and 129 pounds). If you are a large person, or have a very high arch or thicker feet, I would probably suggest you get a lace-up style instead. The construction is very sturdy without much flexibility & they are not overly wide across the bridge of the foot. So, if you are torn between two sizes, I would go up 1/2 size rather than down 1/2 size. I most often wear a 7.5, but I purchased these in an 8 and they fit perfectly.  My pair also came with a useful instructional dvd - an added bonus. And, even my fashionista teenager gave the style a "thumbs-up," so I have to disagree with the reviewer who called them ugly! Even when you are standing still (in line or on the phone, etc.) you can rock back and forth on them, to stretch your legs and get a mini work-out. Also, I did compare them to a similar concept of "air" shoe made by Easy Spirit: the Shape-Ups provided much more of a work-out (greater rocking motion).  Caveat: they do take getting used to, and do "rock" quite a bit, so I would not suggest them for an elderly person if they are at all unsteady on their feet.