I'd probably give these shoes a 4.5.  The problem is that a size US 11 FitFlop is EU 43 and a size US 10 is EU 41.  Well, I wear an EU 42 (which is typically what US size 11's are.  So these shoes are a bit too long.  The heel strap velcro does not extend far enough to tighten them up the way I would like them.  But, even loose, they are comfortable and I do wear them a lot.  My problem with these shoes is not the shoe's fault - they're just not quite right for my feet.