I had not tried this style before and am I ever glad I did.  I love Crocs and wear them almost exclusively.
I normally wear a size 9 in Crocs (8-8 1/2 in regular shoes), so I ordered a 9.  It was a perfect fit.  It has a removable sole.  I would not recommend this shoe for a wide foot.  It would seem to be a better fit for a medium or narrow width.  It is an extremely comfortable shoe.