how do Bounty Hunters work?

I read that bounty hunters are actually very powerful. I'd like to know how people use them successfully. I imagine it's only good for battles that you can start yourself, and only if the creature moves (and casters stay still).

Bounty hunters get an initial bonus to trap setting at the cost of five or so ability points each level. Their specialist snare is nice. It deals damage equal or greater than the regular snare, and also has other qualities; depending on level it can slow or hold an enemy, or in higher levels, create an Otiluke's Resiliant Sphere around the enemy, or simply maze them. Personally I found the traps most useful when they held the enemy, since it isn't species sensitive and you can just hold a whole swarm of creatures as they rush around the corner.