Doctor Who has had it's ups and downs and there is some degree of debate as to the nature of up and down over it's near 50 year history.
If you fall in love with it you will tend to stay true to whatever the show was doing when you did and then judge it's up and downiness based on how close it is currently matching what you loved about it when you first were seduced by the show.
Matt Smith has many qualities of the second and fourth Doctors so he is appealing to people who picked up there.
Nine and Tens epoch have many of signs of JNT's eighties era (silly panto) and early seventies Pertwee stories (London/Earth bound with an extended family of support characters).
People who fell in love with Doctor Nine will really love Doctor Sixteen.