The 2008 world champion joined the Silver Arrows from McLaren in the off-season, having spent five years with his former crew.
However, Brawn believes that Hamilton can spearhead an exciting project at Mercedes, starting with the season's opener in Melbourne on Sunday.
"Lewis comes across as a real enthusiast, there's real spirit and excitement about what he is doing. He's a real racer - and that's what I like about him," said Brawn.
"He's someone who clearly enjoys his racing, and I think he now has the added dimension of being involved in a project that we want to take forward a long way.
"McLaren are a great team, but Lewis's contribution to taking McLaren forward was almost exclusively out on the race track. With where we are, there is a lot more Lewis can get involved in and I think he is relishing and enjoying that aspect."
The season starts with the Australian Grand Prix on Sunday.