Smartgun
Pros: Auto-aiming, large magazine, discovers hidden enemies, secondary MANUAL aiming
Cons: Slower movement, auto-aiming targets "body" (no headshots), short-medium range (con/pro), hard to find, very long respawn time
There are definite ways around this gun.
As an avid Alien player, the only time I get killed by this gun is if I'm caught off guard. And that is rare. Speed, stealth, and pounce.
As a pred, because the gun has only so much range, plasmacaster or spear or even mines takes care of the job.
As a marine, sniper rifle takes out any smartgunner. If up close, double-barrel shotgun to the face. When used right, the pulse rifle also wins via headshots. Pulse rifle can also pull off across-the-map kills. SG has a harder time doing that.
The key here is to be Smarter than the so-called, "Smartgunner". Most of the time, that is quite easy, brother.