Doomfist is a front line damage dealer, though at first glance, he doesn't appear to have a ranged weapon like every other hero in the game. Overwatch's next hero has Rocket Punch, which is a forward-dashing punch that can be charged to go further, and it does more damage when it hits enemies into a wall. Rising Uppercut knocks enemies into the air.
His Meteor Strike ultimate is where he really shines - against a tightly packed group, he jumps out of view, then crashes down to earth dealing massive damage.
His second ability channels his internal Street Fighter with an uppercut that would make Ryu jealous. Doomfist leaps into the sky then comes crashing down dealing significant damage to a large area. Oh, and he also has shotguns built into his knuckles as a primary attack, because of course. In a faux news article from the Times of Numbani, Blizzard has all but confirmed that we'll be seeing Doomfist in Overwatch sooner than expected.
Even before his release, Overwatch's story is expanding. In origins and developer update videos, the company explained that Doomfist is from Nigeria and serves as part of the council of leaders that runs the organisation of Talon.
There was a lot more information in the blog post, but this is the most relevant to Blizzard's teasing of Doomfist. For the past several months Overwatch director Jeff Kaplan continually teased and released other characters, but now the jig is up and Doomfist is here!