Saw the movie and really liked it. The Joker was awesome as everyone says as well as Harvery Dent. My only gripe is the cell phone radar thing that maps all of Gotham. It was totally pointless and unrealistic and could have easily been replaced with an eyewitness seeing the Joker, the Joker wanting to be chased (hostages in masks), or tracing the phone call/transmission followed by good building surveillance.
Joker still won in my book. While the boat (lucky) and Dent were stopped Batman KILLED Dent. The Joker stood still at one point hoping Batman would run him down just to make Batman break that one rule. The Joker may not have beaten the city but he made Batman kill Dent by knocking him out the window to save the child.
Harvery Dent is dead. If he somehow survived (no helmet) a simple police commissioner, and a brand new one at that, can't make Harvey disappear into a prison. Even if he is backed by Bruce Wayne's money there is only so much he can do. Half of Dent's face is extremely recognizable and his burn accident was on the news, he needs major medical operations from the burns and from falling off a building without the suit and especially the helmet batman has. They would then need to sneak him into Arkham, bribe a judge or somehow avoid a trial, have the warden and nearly all the guards in on it, and then keep him in solitary permanently or the other prisoners would tell someone. They also would have had to find a way to trick/bribe a coroner and the usual funeral people.