This is actually one of the great things about this character. He is a ****ed up fashist with a twisted world view. A pontificating fanatic, who is convinced he is the only sane and rightious man, among a filthy, degenerated world. He actually wanted to prove something with Gotham. When he said "the city is yours", he tought he was making a valid point about human nature (very similar to what Joker was saying) and behaviour when "the shackles of society" are gone. Similarily to Joker, he wanted to show how false, the civilised laws and structures are. Of course it was all BS really. He was wrong, becouse he wasn't truly setting people free (not really). Gotham wasn't free, it was under a boot of a ****ed up, crazy warlord, wtih criminals running amok, it sure as hell wasn't a place were representative human nature shows through. But as with any fanatic, Bane actions just warped the world to fit and match his twisted, little worldview. He tought the rioting masses and the likes of Crane, represented true human behaviour, but it really didn't. He also didn't care for his own life. He was ready to go out with a bang (literally), and make Gotham his epitaph, his tombstone. Just as real life terrorists and "freedom fighters", blow themselves the **** up, just to futilely prove some point, or shout some fanatical bull**** to the world, so too did Bane, but on a larger, comic, supervillain scale.
As for the hope/bomb theme. I am honestly suprised to see how many people, don't understand this. I mean Bane almost explicitly explains it to Bruce at one point in the movie. It was a mirror reflection of what happened to Bane in prison. "There can be no despair, without hope". He didn't just wanted to blow Gotham sky high. He wanted to torment its people, by giving them false hope, and watching how they behave in that little cesspool he created. To punish the upper classes, the kind of people who he believed were responsible for the misery of the likes of him, in the first place. In the comics, Bane was also a screwed up revolutionary. Nolan's version is even more suggestive, nuanced, real and threatening.
This has been beaten to death allready. A whole large chunk of "Batman Begins" was dedicated to showing young Bruce as a man who is resourceful enough, to make it on his own, in foreign, exotic, hostile lands, without any money or support. The trilogy allready established, that he spend whole 7 years, traveling the world, making it on his own. At this point we really don't need to have another trip, explained and showed to us verbatim, especially in a movie thats allready condensed with so much (a bit too much) plot, that it has no time for such bs.
It was in no way impossible, it wasn't even anything especially hard for someone like Bruce. But it probably was pretty uncinematic and mundane. Do You really need to see Bruce spend time making this thing? It was necessary tool, becouse of the dramatic effect it had on the citizens. The making of it, probably wasn't so.
Ok. Point for You. I also didn't entirely like it. The only reason it happend was becouse "that's what was written in the comics". I really wish Nolan would have ignored this piece of cannon. I guess it could be explained, that it was some twised way of really getting inside that guys head, getting real close to him, knowing him perhaps. She was after all, a crazy woman. It's entirely possible that she both hated him and was also at the same time, fascinated by him and drawn to him, in some way (which would also fit the comics if I remeber correctly).
Seriously? Thats a real argument against the film? How many times Nolan has to make this point. The voice is not just a theatrical tool for deception. Wayne is a bit of an animal, when he's Batman. He becomes something else when he puts on the cowl. He lets the inner beast out. That's not just a vocal trick, thats his persona, thats how the thing he becomes in the suit, speaks.
