Picked up the game Friday, and yes it is a lot of trial and error and you do end up restarting several missions over BUT the feeling I get playing the game, the chases, linking together moves is just plain amazing for me. When I get to a point that is frustrating me, like any game, I just turn it off or go do something else. When I come back to it, I solve it immediately.
As stated before, the levels are pretty huge BUT you are flying through them as fast as you can so it doesn't help the length of the game either. I am also glad that the game isn't open world because that brings into the equation a whole other list of issues IMO. It would turn into a game without a purpose. I like that there is a somewhat linear path with multiple variations to get to the destination.
Time trials are highly addictive for me. Going through the first time trial "Playground 1" My first time was in the 3 minute range....ouch. I dropped it down to 2:52, and then 2:23. After looking over the level and with about 3-4 more runs I was able to drop it down to 1:09. I think I can go even faster if I can keep the momentum going.
All in all, I am glad I purchased this game. I hope it does well enough to warrant a sequel because I would love for DICE to resolve everyones complaints, learn more about what they were trying to accomplish and give us a better Mirror's Edge. Make it happen EA.
Edit- Actually, IMO DICE got it right, I don't need a sequel to fix or confirm what I enjoyed. I just want a sequel to continue the experience I have with it now, if that makes sense.