Houllier signed Bent from Sunderland in January.
He told the Birmingham Mail: "Bent's goal ratio speak for itself and he's a good man too. "I think he will improve because he listens. If you give him a few tips and a few details he'll try to get on to that.
"His movement is outstanding. If you press the red button when you watch Sky to follow the movement of a player then you should watch Bent because he gives a lesson to other strikers. It shows what a centre-forward can do during a game and he's very good at it.
"I think he's improved since he's been at Villa. He's more aware of his duties, he's not just a fox in the box.
"The way he links with the other players and his movement.
"What I like about him is he can play as a holding striker and sometimes he can go in between the defenders, drop deep, run towards goals and push forward."