I bought the Origins Edition myself. Though the gameply looks basic, it's an entirely different thing when you play it.
What really gripped me was the attention to detail. How the enemy's footsteps are louder than your own and your teammates, allowing you to perceive them ahead of time. Every sound in the game is...oddly satisfying. From the crisp and unique booms, bangs, and pews every weapon makes, to the distinct "dink!" you hear every time you score a hit.
The characters are really enjoyable too. Though you won't get much lore from the game alone, you will get some fun and well voiced dialogue before and during the match.
I find it refreshing to see a majority of the hero characters so positive. So full of good energy and will to help the world. On the other end of the spectrum, it's fun to see villains you love to hate. Baddies that make you wonder what made them into what they are, and what their thought process is. It's all a nice break from the brooding nature that surrounds a lot of shooters I've seen recently, while not being full blown comedy clowns that you can't take seriously. There's a good balance.
Ohp..heh. Guess I typed longer then I meant to.
TL;DR This game has great sound design and fun characters.