I own many pairs of shoes and quite a few fitflops.  i read the reviews before ordering them and was a little concerned, but these are perfect for me.  i have flat rather narrow feet and have no problem getting these on my foot.  They are super comfortable and I can and do wear them to work as a psychiatric nurse.  As far as the "toning" benefits - I don't know or care.  Their comfort is enough as far as I'm concerned.