Well, I had the Reebok ones, and they were super comfy for a few months. Then my foot started to hurt a little...then a lot. I now have the never-healing stress fracture from hell and severe plantar fasciitis (as in, I'd like to saw my foot off with a dull hacksaw kind of pain). I've seen several doctors and physical therapists, including an orthopedist and one of the top podiatrists in the country, and ALL put blame on the shoes (especially since that was the only change in my life).
Now I've got to live with this foot, and it's just a big cycle with the stress fracture. The chronic pain is awful.
I would rather have my feet amputated than wear any of these types of shoes.
From what I gathered from my doctors and therapist, my injuries have been quite common among people wearing these shoes. Podiatrists and orthopedists HATE them.
(for the record, I didn't buy them to magically lose weight. They were originally quite comfortable for my high-arched feet.)