Roxas is still pretty much a sweet dork, but he has gained confidence and maturity in his time in Vatheon. A lot of this is thanks to all the friendships he was able to make (and in some cases to continue), most of which were longer, deeper, and more open relationships than he had any opportunity for before. He can still be awkward with people, but it doesn't discourage him from trying, and though he doesn't trust strangers immediately, it's easier for him to give them a chance. His friends mean a lot more to him now than his own self-knowledge, and he would never abandon them. He still isn't sure if he could do what Sora did, and sacrifice himself for them. Maybe.

He's experienced more in Vatheon, and in particular felt more. Falling in love with Axel probably provided him with his biggest confidence boost, despite his rejection. A feeling he never experienced as Sora is proof for him that he does have the capacity to feel, and although he may not be Sora's equal, he may still be whole in his own way. Before, expressing his opinion was always tempered by the thought that he was incomplete as a person, and might not know as well as others even if he'd gone through the same thing. Now, he thinks his opinion is just as legitimate as anyone else's, and maybe he can fully understand the feelings behind other people's. He's started to become more perceptive that way.