I have purchased 3 pairs of Fitflop sandals (black, silver, and brown), the first pair about 5 years ago when they first came out.  Since then I've been wearing them everyday (therefore I needed 3 different colors, to match my outfit). I do a lot of walking - shopping, running errands, walking trips, sightseeing - and they prove to be the most comfortable among all my shoes.  This time I decide to order boots because I never got to wear sandals during the cold winter months.  I took other customers' advice and ordered half a size down (I am a 5.5 and I have skinny feet so I ordered a 5), and they fit me perfectly.  They feel soooooooo comfortable - the first day of wearing already feels like wearing old, worn, familiar shoes - if you know what I mean.  With other shoes, usually I will get back aches after walking for a few hours, but my back never aches when I am wearing Fitflops, and I could walk for hours and hours.  There must be something particularly effective about the design of the shoes.  I will recommend Fitflops to everyone.