I'm not surprised at all. Season 3 completely ruined the show for me. Season 2 started off very promising with the introduction of Adam, but was harmed by the writers strike. But 3, it was dreadful and it's never recovered.
I'm very much not surprised yet a little relieved. Although the last season was getting slightly better, it was a chore to watch and yet I felt the need to keep watching in order to see what happens. But a world without Sylar is a very sad one.