I have a pretty enormous head and this hat fits well.  It also covers my neck from the sun and helps keep away mosquitoes, and I would not go on a hike or to the beach without it at this point.  You will get some comments and an occasional funny look, but function trumps all.  Let those slaves to conformity get all the sun cancer they want, this thing is comfortable and healthier.

The neck cover can get a bit tangled when you take it off and put it back on, but it is easy to sort out.  It is a very light weight hat, but it can also get a bit sweaty just having your head enclosed on a hot day.  The neck cover is very easily removable via two snaps on the brim though, and with it remove this is just a very lightweight cap.