I pre-ordered it on the Bone. What it lacks in depth it definitely makes up for with some ridiculously fun gameplay. It's like an FPS version of Smash Bros.
So far my favorite character is Torbjorn when defending, and McCree on offense. It does have some balance issues, though. Roadhog is ridiculously strong. He can one shot most characters with his shotgun, can self heal, and has a shitload of life to begin with. People say Bastion is OP, but he's just really straightforward and easy to play. Tracer is supposed to be the MVP of Overwatch, but she's pretty weak imo. Her teleporting nonsense is kind of annoying, but I never really feel threatened by her. Zenyatta is probably really OP, but he's so hard to use it doesn't look like anyone has mastered him yet. Reinhardt is pretty great and a good counter to Roadhog.