the whole idea behind it. Thor was tired of the cycle of battle and wanting an end to it. Banner proved himself the truer hero by willingly merging with the Hulk to show how true heroes act by giving up his own personal heaven to go back to his living nightmare. Hence, why Odin saluted him at the end. Add on that Odin was moments from waking up Banner saved Thor's life when he didn't have to. I was more or less their thinking.
"Banner saved Thor's life when he didn't have to"
---But that's true of any superhero comicbook hero ever created (even Spawn). They save people. They don't have to, but they do it anyway, exposing themselves to threats in doing so. In the DVD, Thor went out of his way to save Asgard, willing to give up his own life, Thor didn't learn anything new from Banner. Banner, was in fact unwilling to merge with the Hulk at first. It was only when he needed to save Thor which prompted him to do the right thing. Difference, Thor was willing throughout the movie. Banner, only during that one pivotal moment.