Mangle doesnt bring burst, it brings dps. When playing a feral I feel like something of a glorified pet, my job is just to sit on a target while applying infected wounds and rooting pretty often. Rogues get more fun utility like sprint, Sstep, kick and gouge. I found it more fun when we had HT (it healed like a truck even when it wasn't instant), but meh.
Anyway, as i said, it's definately a useful spec and to those that enjoy it, that's good. I'm glad that you enjoy it. Carry on.