I'm barefooting a little round Crete with my Family.
So far I'd give it a rating of 3.5 on the difficulty rating (from 1-5). It's very rocky and stony in a lot of places that make travel somewaht tentative. The major cities are quiet easy, however, with relativly little glass and quite little free. Cirtainly the touristy bits are very well cleaned. What glass there is tends to be very tiny rounded bits rather than the freshly smashed bottles which are much more of a problem.
There is also a lot of sea around (it beaing an island and all), and it's such a joy not to have to worry about putting on shoes after swimming on a beach as the sand wears off in it's own time on the way home. Nice.