Mirror's Edge: Catalyst (opens in new tab) makes a lot of changes to the first game's formula. It drops you into an open world, revamps the combat, and introduces a level and skill system—but through all that, it still manages to feel like Mirror's Edge.
No longer linear, Catalyst's story is told through specific missions that can be unlocked on the world map. The video above is the complete, uncut gameplay of one of the missions available in Catalyst's upcoming closed beta, and should give you a good sense of what it's like to find a mission, complete it, and get back to base. This is one of the first few missions in the game and comes complete with Catalyst's surprisingly high-quality cutscenes, so be wary of early-game spoilers.
For a spoiler-free look at Mirror's Edge: Catalyst, you can watch the video embedded below to hear my thoughts and impressions after playing the game for a few hours. Also be sure to read Sam's written impressions (opens in new tab) of the game, as he had a slightly different opinion about its open world than me.