I had my Five-seveN out last week and was reminded how much fun it is to shoot. Amazingly accurate at 25 yards, and capable of further, very little recoil and 20 rounds between reloads.
As for ammo, rumors keep going around that other manufacturers are going to produce the 5.7x28 but so far only two that I know of. As for price, a 2000 round case of the stuff was available on sail for under $725. For some reason the price skyrocketed to just under $900!!! Of course, some good .223 is about the same price, and many specialty rounds even more.
You on a boat?