So, I was afraid they would be too narrow. I own 2 pairs of regular Birkenstock Gizehs and they fit me very well, (I guess I have wide feet) so since these are arrow width, I was skeptical.  However, these fit nicely because they have that adjustable strap across the foot.
Aside from that- the EVA material is actually comfortable! Its like crocs, but required more breaking in. Like other Birkenstocks, its worth the few days of achy feet to have your shoes mold to your foot. These got softer quicker than regular Birkenstocks.
Id recommend these Madrids for hanging around the pool, and the house.  Its really great having a pair of Birks that can get wet!
Also- I usually wear a size 7/7.5 womens. BUT for Birkenstocks: all 3 pairs in size 6/6.5 (37) fit perfectly : )