I want to try it out myself, but post 50 you get the casting stance(as does bard), and that just makes me shy away. I don't like casting spells very much haha.
You only have to cast around half of you attacks as mch, slug shot and clean shot procs have no casting time so between the 50% proc rate and your ammo making it 100% you still have plenty of mobility, vs brd where you have no GCD abilities without a cast minus lolfeint which makes everything super tight (seriously if I'm off on timeing by like .5 seconds my opener is botched). Damage wise it's around the same as brd but more bursty so it has an advantage in fights with lots of breaks, but if you have even 1 caster in your group bard works out to more group wide dps (assuming everyone is equally geared/skilled etc). It also comes with a couple damage debuff abilities, a stun and knock back and it's versions of ballad/paeon are off GCD are bonuses for progression.