My son is 3. He is a stereotypical young boy. If he can climb it - he does - and then jumps off it. If it can fly into the wall, he'll help it get there. But, give him a puzzle and he turns into Rainman. He'll sit there for an hour putting all the pieces together, quiet as a church mouse. It's pretty impressive too. He definitely didn't get that from his dad.
Currently there is one completed puzzle on the floor in their toy room and another half completed one in front of the pellet stove that I interrupted him doing to get him in bed.