Here is a list of things we know about Mario as a person:
-We know he really really likes Peach, possibly to the point of being enamored.
-We know he really likes pasta, seeing how he dreams about it.
-We know playing sports or getting in fights gets him really REALLY hyped up, if his constant angry expression on all the boxarts is anything to go by.
-We know he's a very friendly guy, given his usual warm greetings to us the player.
-We know he might secretly be an egotist, given things like him stepping on Luigi's foot in Mario Power Tennis.
-We know he's almost hopelessly devoted to Peach, since he seems to reject any other women that make passes at him.
-We know he can be aggressive to the point of being thoughtless: "Who do you think you are, Bruce Lee? You can't go in there with your fists flying!"
-We know he's a really good pantomime actor, according to Super Mario RPG.
-We know he can do [darn] near any job you throw at him, given his numerous roles he's taken on.'
-We know he has some pretty unbelievable strength at his disposal. He can throw Bowser, for cripe's sake!
Anybody else has anything to add to this list, be sure to point it out.