Looking before leaping doesn't make for a particularly exciting game
Essentially, the problem with Mirror's Edge is that its ambitions are twofold, and the two parts just don't get along together. On the one hand, Dice wanted to give the player a relatively open environment with multiple pathways through an area and lots of necessary exploration. On the other, they wanted to create a platformer that revolves around the notion of speed and momentum. While those two idea occasionally work well on their own throughout their game, when they both compete for attention then Mirror's Edge becomes a real mess.
By far the most exhilarating and thoroughly enjoyable part of Mirror's Edge is when you are presented with an obviously defined path and you just run. The controls are fine and the sense of speed is great. Bounding over fences, sliding through gaps, and launching yourself from building to building in death-defying displays of athleticism is purely, simply fun. New obstacles suddenly pop up fifteen yards ahead, giving you just a second or two to decide how to overcome it.
Unfortunately, sequences like these are relatively few and far between, because of the quasi-open world concept that Dice has implemented in Mirror's Edge. While there may be one path that you're generally supposed to follow, there are also a lot of red herrings: buildings that you think you can reach but actually can't, or fences that you search for ways around only to discover that you're supposed to head off in some other direction.
Needless to say, this is really annoying. In a game that's so enamored with speed, it's awkward and stupid to stand still for thirty seconds, slowly panning the camera looking for a jump you can make or a path to proceed along. In attempting to give players a sense of space via lots of open rooftops and a large, "open" city, the developers completely ruined the pacing of the game and did more harm than good.
In an attempt to deal with the problem of having no freaking clue where to go next, there's something called Runner Vision which allows you to tap a button and be automatically pointed in the right direction. Unfortunately, this really causes more problems than it solves. Say you're running a long the edge of a building and want a general sense of where you need to go next. It happens to be the top of the neighboring building, but to get there you need to head in a different direction and do some roundabout platforming. But hitting the button for Runner Vision points you to that building, automatically turning you off the building you're currently on to meet a sickening death twenty stories below. Believe me when I say this is really freaking annoying, and it does nothing to solve the problem with pacing. In order to ensure you don't meet an untimely death, you need to be standing still in order to use Runner Vision, meaning...yeah, there's still a pacing problem.
All these problems come together to create a trial-and-error style of gameplay. The checkpoint system is serviceable, but there are some occasions where you'll find yourself ten minutes back because you missed a particularly tricky jump. The controls don't to much to help, largely because they aren't all that intuitive. Once you get used to them you'll find yourself pulling off wall jumps and impressive platforming feats with ease. But for the first hour or so, you'll be treated to the sickening crunch of Faith's body hitting the pavement several stories below because you couldn't get her to do exactly what you needed.
Essentially, the platforming in Mirror's Edge suffers from massive inconsistency. A few sections of the game have only one obvious way to proceed, allowing you to fly across buildings and maneuver around obstacles with breathtaking ease. These portions of the game are absolutely amazing and really do represent a lot of progression for the platforming genre. But these segments of the game only make the confusing, "where-to-go-next" areas all the more infuriating.
There's never really much plot development, and all you really know is that there's some conspiracy going on, your sister's been framed for a murder, and Faith, a Runner, needs to clear things up. So she runs. And runs. And runs. All the while, she's under fire from the city's police force, which brings rise to some of the most frustrating portions of the game. It's ridiculously difficult to pull off a wall jump, turn around in mid-air, grab a bar, and use it to swing across to a nearby rooftop when there's a chopper twenty feet away from you plugging you full of lead.
These moments may very well make you want to take the controller decimate it with your brother's baseball bat. But your revenge comes in the form of Mirror's Edge combat system, where you can gracefully take out on-foot police. The developers would like you to take down these "blues", as they're called, with a variety of fairly complicated acrobatic maneuvers. But in reality, what you'll find yourself doing is isolating a policeman, landing a flying kick in his face, then using his dropped shotgun to take out all his buddies.
This might not actually be all that graceful, but it sure is fun. The gunplay and combat isn't all that sophisticated or even particularly interesting, but it succeeds because it's consistent. Stealthily hunting down a single soldier or kicking a guard off a building is exciting, even if it may not really be in the spirit of Mirror's Edge.
In addition to the inconsistent gameplay, Mirror's Edge other significant fault is that it's quite short and the learning curve is relatively steep. After a while, you may have mastered all the techniques and may find yourself having a lot of fun running through the different levels...only to see the game end an hour later. It's difficult to justify purchasing Mirror's Edge, because it ends shortly after it really picks up its stride.
What's sad is that there really is some replay value in Mirror's Edge. Once you've figured out the fastest and most fluid way through a level, speed runs can be a lot of fun. But the first time through, Mirror's Edge is a mess of false starts, disappointments, and bewildered head-scratching. As a result, it's easy to just give up before you really see everything that the game has to offer.
Barely an hour into the game, I almost closed the book on Mirror's Edge. But ultimately I went back to it, and I'm glad I did. Mirror's Edge is not a great game – it's not even a good game. But ultimately, it's worth trudging through some of the really frustrating bits just to experience the few moments of truly unparalleled excitement you get from playing Mirror's Edge.