Moose is right. You can mash buttons in the first few levels, but you'll get your ass handed to you not much later. Fiddling around with weapon and power combinations is great - I recently rolled a undead commando who combines gadgets with rifles and he's tons of fun.
[You must be logged in to view images. Log in or Register.]
The rifle gets some fun combo's that constantly keep your attention on the game. You can't play it like WoW (or EQ), where you casually keep on spamming immolate or frost bolt while also doing other stuff. It also demands teamwork ^^ good stuff.