First of all, Two-Face is batshit (pardon the pun) crazy. As he states in the film, the only fair thing in this indecent world is chance. So he lets the coin decide the fate of his victims. The coin spared the Joker and Ramirez, Wurtz wasn´t as lucky. He blamed Gordon because he let the suspicious and very possibly corrupt cops (Dent warns Gordon that Wurtz and Ramirez are "scum" early in the film) to work close with him and thus indirectly being responsible for Rachel. Two-Face knew all the time Joker orchestrated the whole thing, but he wants the people who let the mad dog loose (and that includes Batman as well).
The one thing that bothers me, although the scene was pretty badass, is the way he deals with Maroni. The coin decides that Maroni should live, but then he takes out the limo driver (who had nothing to do with him), thusly giving himself a second chance to eliminate Maroni. That time he wasn´t a slave to his coin, which is the essence of Two-Face´s character.
Batman was a nemesis to Gotham long before Two-Face´s death. He would never be recognized as a hero, unlike Harvey Dent, who was Gotham´s favorite. That´s why Batman decides he should take the fall for Dent, making him the hero and giving hope to Gotham. Morally it isn´t the perfect choice to lie to the people - but everybody is far from perfect in this film.
Writing about it makes me wonder how much subtext can be found in the film. It really stands out from all other superhero movies.