Pain plays fast but generally isn't clicky. It doesn't have all the slow "setup" issues that some sets have. (i'm looking at you Rad toggles).
Lots of buffs and heals (pbaoe heal and single target). A healing aura that doesn't detoggle if you get mezzed. a pbaoe enemy debuff. pbaoe team buff. a nice combat rez. It likes to play in melee and with a res armor it holds up reasonably well. nice damage boost for the team and a single teammate "murder buff" (+dam, +to hit ,+regen). A "clear mind" type buff that does more than just that. I feel like it's what empathy should have been.
pair it with sonic for the stacking -res debuff on baddies. it's a little engine that drives teams. I'm frequently the only support toon on 8 man teams and we roll.
IMHO it's quietly a little OP...not much...just enough to make it really fun. 🙂 Your mileage may vary.