I agree to that, he's just immortal. If we are speaking of developing powers, I guess immortallity just goes with the healing factor. The only bizer thing I can think of having a healing factor is the power to generate other self-organic structures, like bone panzer and multiple arms, but I wouldn't go as far as that.
As for his powers and motives as Bob mentioned them. Adam is immortal, it wouldn't be weird if he just thinks he's god because he can't die. Even being burned totally was not enough to burn him. What does strike my mind is that Peter and Clair, both having a healing factor only heal when the damaging object is removed from their body. Though, when Peter was shot, he healed and the bullets came out of his body. It would be logical to think, that the bullits should have been removed.
As for Matt, it's pretty logical that he has the power of telepathy, I stongly disagree with the fact that he learned that himself. He just had the power in him the whole time.
As for favourite characters. I like Matt's acting. I just find Claire sexy (allthough she's almost 40 cm shorter as me :p). As far as powers I could say I like Peter best now. His telekinetic, healing, timetraveling and electric manipulating powers just rock. As far as personality goes I just like Adam best. First he is a drunk Brittish dude, who just stranded in Japan and after that he turns out to be the main villain. I was a big fan of the feudel Japan scenes anyways, Hiro rocks.
Hmm, conclusion: I like a lot of guys. Actually the only persons who irritate me are Nikki and those Mexican shits, Sylar better be killing them quickly.