I really enjoyed the original and have been wondering what they'd do for a sequel because I actually liked the story too. The story aspect problem with the sequel is that it would have to shift the story a bit from Faith and have it be more about the city and the dystopia.
I got the impression that the EA team is looking at two different aspects to make the sequel better. The first is to tighten up the game play mechanics. The second is to attract a bigger fan base. As I've scanned through the posts here, I've seen many comments about the mechanics and I think the assumption is that if the mechanics are improved then the fan base will improve. This line of thought has strong merit, but I don't think it's the only valid line of thought.
I always thought it might be interesting to see EA do a little more with the Mirror's Edge intellectuality property. I don't think a movie would work, but a competition based television show might be interesting. Think American Gladiators crossed with Ultimate Ninja Challenge/Sasuke, or maybe just some free running reality type show where contestants compete each week for the opportunity to run the big Mirror's Edge challenge at the end of the season. This probably isn't my best idea ever, but I'd like to see it.
As far as the mechanics of the game go, I think the biggest problem was peripheral vision. Free running requires the participant to be aware of and interact with the environment quickly and accurately, but the game limited the player to seeing what could be displayed on a rectangular screen. Perhaps if runner's vision had an adequate way of enhancing Faith's peripheral vision, then the game would have been more welcoming.