I absolutely adore these - so comfortable!  I hike and garden in them.  I love that they are machine washable.  I haven't worn them in (e.g.) the ocean, because I didn't want my favorite sandals to acquire that pleasant ocean smell.  So I can't comment on their usefulness as a water shoe.  They didn't require any break-in time, and after a couple months of very frequent wear, I don't notice a difference in how they feel or fit.  I ended up with a half size lower than I buy in other brands, so I would recommend trying them on before you buy.