I had a FiveseveN IOM for a while. I got lucky and found some ammo for $18 per box of 50. Not too bad, considering that the SS192 hollowpoint round is a duty round. It's about the same price as the good Federal or Corbon JHPs in other calibers.
It's very light, the exterior with the exception of the sights is completely enclosed in plastic. So if you are worried about corrision from sweat it's a plus. Good single action trigger, the front sight is huge. The Klinton 10 round mags are a liability. Get the 20 rounders if you can.
The 10 rounders are a terrible design with the floorplate held on with 2 plastic tabs. These are weak and you can end up with all your ammo popping out the bottom of the handgun at the worst moment. It happened to me once at the range, at first I thought I had kaboomed because ammo went flying everywhere. But it was just the magazine breaking.