I'm so sorry for linking to Kotaku, but that's where I first saw this.
Since you won't read it, here's the important parts:
-Free to play (you can buy character taunts, skins, weapon effects, endorsements)
-Five-on-five instead of six-on-six
-All new arenas
-New bots- Fujibot and Shady
-There will be three new characters at launch, with more added over time. (original cast is still there)
1. Combatgirl, a playable version of the first game's Pitgirl (a clone, according to the new game's story), who fills a support role and has her own turrets.
2. The Veteran, is a former champion wrestler whose abilities are based on a grappling. He's even got a grappling hook to pull his foes toward him.
3. The Gunslinger, is a new sniper who isn't as powerful as the original MNC sniper—who returns in the new game. Her advantage is that she can shoot quickly. She wields two pistols, a love gun and a hate gun, which are tied to special abilities that kneecap people to slow them down, shoot waves of bullets and more.