The assault rifle isn't entirely different in function from that of the Pulse Rifle except that the controlled bursts are much more condusive to longer ranges. With that said, range is not something you frequently have in this game so its likely that you'll use the Pulse Rifle MK2 instead. The main appeal of the weapon is that it has some good alternate fire modes, including an Incineration Unit and Frag Rounds.
Despite the limitations on this weapon against Aliens, it is a rather useful weapon against humans who tend to fight at a longer range.
