The plasma pistol is actually one of the best guns in the game. It's impeccable at close range, (charge up and punch,instant kill) You can pair it with any human gun and have a deadly combo, and if you pair it with a BR it's for sure the most versatile/deadly weapon set in the game.
Yeah, its kinda like the sword. You can hear when someone equips it if you are close enough. You can hear the buzzing from the charge if he is aorund the corner.