I think that in early seasons several of the characters seem different, but for the most part it is due to us not knowing the characters very well. As times goes on we see the subtly in them. However, I feel that both Cameron and Wilson changed significantly. Cameron became very confident and less naive than she had been. The former because she got out of House's shadow and off the team, and the latter because of the time she had spent on his team. So for me it makes sense. Wilson lost his relaxed demeanor that he had in season one alongside his easy going way of dealing with House, but that could be explained by his dissolving marriage/Volger/Tritter all in quick succession. My fannish heart says that is was also the time that he actually fell in love with House, and that precipitated depression which fundamentally changed his world view as he became far less optimistic/hopeful.