Yes I missed Charlie Sheen from the 9th season. I just carried on to finish at least the season for sure but ended up watching upto to series finale.
The point was, Ashton Kutcher kept it engaging even when Charlie left. As it was a long run, it was obvious the show will lose some spark as it approaches it's end. Still I had my laughs in the final season and the final episode was lit. They mocked a lot about Charlie Sheen.