I liked it, but I do feel it was the weakest of the trilogy. It was riddled with plot holes and unresolved themes, which I'll try to keep vague:
How did Batman get back into Gotham when they made its isolation such a story point?
Why didn't the villains leave Gotham in the months they were there since they knew it was a matter of time?
Why didn't Fox just flood the reactor?
Why did Bruce and Selena end things as they did? Where did that come from?
How did Bruce know the location of the cafe Alfred used to visit?
Why weren't there guards at the exit of the prison?
Why is the prison that is supposed to be the deepest hell on Earth full of friendly, helpful people who will feed and heal a crippled man while everyone else roots for you to escape?
What happened to the Scarecrow?
Why did everyone on Gotham instantly believe the letter Bane read?
Since we've established repeatedly in all three movies that Bruce needs to be Batman, why does he end things as he does?
Possibly worst of all, and this is largely because of Ledger's death and Nolan was just dealt a bad hand here, would it take that much rewriting of things to cut Dark Knight out completely? The city would just have to be clean because of Batman directly and Rachel dead/gone some other way and it lifts right out.
I think this movie needed at least another round of rewrites, though I'm hoping that the rumors of a much longer version are true and that we'll see it on DVD. That might help a lot.