"You look Time Lord."

Different head writers, of course the program has changed. Just as it changed when it went from Black & White to Color.

Just as it changed (In my childhood memories) from Four's time to Five's time.

Just as it changed from "Survivor" to the Television Movie to the 2005 series.

But it's a bit of apples and oranges. It would be best to compare Series 5 and 6... and Moff's other works - not the whole series.