The mystery surrounding Danzo was pretty much unraveled at the time of his death. He was a man who worked for the greater good of Konohagakure through its shadows. Hiruzen was diplomatic and kind-hearted, whereas Danzo did the things that had to be done, no matter the cost; together, they were a team -- "Hiruzen in front, and Danzo in the back".
For example, Danzo and Hiruzen differed on the annihilation of the Uchiha clan. Hiruzen believed there had to be another way...with his optimism, it is possible that the Uchiha's coup could have went off due to his indecisiveness, causing a great bloodshed within the village, which would ultimately result in the Uchiha being crushed (and the other side would suffer a great loss as well). Danzo strongly believed that the Uchiha coup d'etat had to be stopped in its tracks, in the most effective way -- using their double agent Itachi to massacre his own clan. In the end, Hiruzen was outvoted and Danzo's plan was to be carried out...despite the price it came with, Danzo had the village's best interests at heart and chose the lesser of the two evils. It was he who gave Itachi his choice: stand with his clan and be annihilated with them, or betray his clan and save Sasuke. Itachi chose the latter.
By giving Itachi the choice to save Sasuke, Danzo showed that he had some compassion. While he could have easily ordered the ANBU to wipe out the Uchiha, he offered Itachi an alternative where he could save the person he loved most -- his younger brother. Danzo kept his word and never harmed Sasuke, despite the fact that he was a growing threat against the village. Until he sent Sai on his 'secret mission' to kill Sasuke.
By that time, Danzo had realized that it wouldn't be too long before Sasuke had turned into what he feared -- an avenger who would stop at nothing to destroy Konoha. While it meant going against Itachi's wishes, which would prove to have severe consequences, he was prepared to kill Sasuke for the greater good of the village. Of course this plan failed, and Sasuke continued living.
The next time we really saw Danzo was Pain's attack on the village -- he refused to help, so that the village would be destroyed and he could rise up as the new Hokage. This sacrifice was all in the name of the greater good but it had now been warped into a desire for power -- he felt his methods were better and that Hashirama's teachings were pretty words that were unfit to lead the village. In the end, his plan succeeded since Tsunade was in a coma and he was unofficially pronounced 6th Hokage.
At the summit of the 5 Kages, Danzo attempted to take charge of the Alliance per his usual backdoor methods (Koto Amatsukami) -- once again, in the name of his village and the greater good. Of course this failed and he ended up fighting Sasuke. By now, Sasuke had learned the real truth of the Uchiha massacre. His initial goal of killing the man who wiped out his clan was null and void -- his new goal was the village, mainly the elders Danzo, Homura, and Koharu. Danzo's greatest fears had come true; Sasuke had learned the truth and was out to get the village. Thinking that Itachi told him the truth, Danzo admitted that what Sasuke believed was correct, and ultimately confirmed his motives of revenge against the village. In his final moments, through his flashbacks, we saw that deep within, Danzo was a man who did everything for his village -- no matter the price, or the pain he had to bear. No matter the sacrifices. He did what had to be done, and he never thought twice about doing it. Down to his dying breath, he tried to eliminate Konoha's greatest threats (at the time), Tobi & Sasuke -- at the price of his own life (self sacrifice). This goes to show that Danzo was not a hypocrite; he was willing to sacrifice himself just as readily as he did with other people, as long as the price was right.
Danzo has my respect. Although he became power hungry and his methods to bring about the greater good became twisted, he always had the village's best interests at heart. And he truly cared for his one and only friend, Hiruzen Sarutobi.
tl;dr: Danzo is a boss.
