It is a fabulous series and should keep on running for at least 3 more years. The acting is great, but I agree with Edward B. It does need some fresh blood. And, Charlie's math things are sometimes kind of hokey. But I love Megan, Colby, and Don.
Don't get me wrong but how many times can you create new number and keep it fresh. The cast is good the acting is good, and the chemistry between these actors is outstanding. I;m waiting for the day he figures out something that the Greeks had not already figured out 2500 years ago.
But its worth watching just for the acting. What is needed is fresh blood.