While my last pair have not totally been worn out, I can tell the difference compared to the new pair.  The massaging nubs in the footbed are not as effective after 2 years of very regular use.  Ditto for the soles, the new ones have a a bit better traction.  Other than those tow thing, they look new.  The best things about this style of croc are the lack of holes on the top of the shoe and the higher back (at the heel).  I do not use the strap unless I am climbing a ladder or something else potentially dangerous if a shoe falls off, so the higher back is great.