It's a great concept, which you already knew. It's also a good game but not without it's flaws. To sum up my thoughts on it, the IGN review pretty much nails the way I feel.
Link;
IGN Video: Mirror's Edge PlayStation 3 Review - Video Review
The game is always fun, except timetrial which is just infuriating when you're on for a kickass time and then you make a mistake right at the end, but the story is very short and very.... how to say... Ok - you've got this huge city that's run by a very strict big brother-esque governement with elections for mayor approaching and the assassination of one of the top candidates, "Runners" who work for clients - whom we're pretty much told are doing pretty important stuff that they don't want the government to know about, I'm pretty sure I saw something in an elevator about a Resistance group.... But all of this takes backseat to the over clichéd "I'm going to rescue my sister".. Though as I understand it, the game is supposed to be the first in a Trilogy, so maybe this is just setting the groundwork and introducing everything.
The only other real problem I found was the lack of moves in Faith's repetoir (sp?), it consists pretty much of Jump, Duck, Run.. 3 basic moves to accomplish everything in the game... Yes those 3 things can do pretty much every task set to her, but an extended move list would definitely be a welcome addition to Mirror's Edge 2.
Overall; Good game and shows great promise for future releases, like a rough diamond that needs polishing up to sparkle. A very solid first step to an arguably new genre of gaming.