He was my second unlock, I think he's got the best specialist weapon. You have to make sure you kinda hide the swarms in bottleneck/heavy traffic areas. Stick them on the ceiling, behind boxes, etc as the radius is fairly big. If you just drop them in the middle of a hallway then people will see them and destroy them before getting close. Then you need to step back and play defensive, don't rush. Stay away from the lane where you laid the swarms and try to hold the other two lanes (which will force the other team to use your swarm lane).
You can also set them on one side of the map, and if you get bored patrolling that side, rush to the other side and flip the spawns, then they'll spawn on the side with the hives and you'll get kills. I'd say in a normal TDM game I can easily get 5-8 kills with the hive, but some games even more. I even run Overdrive so I can reload the ability faster. It works great if you're patient, but if you're someone who likes to rush it's not too valuable.