I get BBC America, so I'm at season 3. Haven't seen 4 yet, and if it goes on leave for a bit I'll resist the temptation to watch them on SciFi so I can stretch them out!
I grew up on Doctor Who, my wife hasn't got the concept yet that assistants come and go. She hated Rose leaving...then started liking Martha, then she left. I'm not sure if she'll like Catherine Tate. I prefer British comedy, but I've never been a big fan of Tate.
As for Tennant, I'll say he is my favorite Doctor since Tom Baker (#4 of old series). I like how he has this lighthearted comedic sense to the role. A sarcastic geek I guess you could call it. Eccleston is a good actor, but better suited in serious roles. Doctor Who should have a little bit of an easy going feel to it.
And my 4 year old runs around going "exterminate" sometimes.
