Very comfortable.  Sturdy and sporty design.  No disadvantages of regular flips flops.  No lower back, knee, or hip pain after walking 9 miles in one afternoon.  Worked out calves more than regular walking.  My core feels a slight difference too.  Not sure if my core would feel anything if I had only walked 1 mile, though.

They don't sit on your foot in the same place as regular flip flops- which take a little to get used to- but no big deal.  A bit of blistering on the top of my foot (that happens with all new flip flops though).

Some people say that they are a bit pricey but I disagree. ...