near the end of season 3. I thought it started a bit slow, but that's to be expected since the Doctor was "mourning" for Rose and was kind of cold towards Martha.
Things picked up with Gridlock. A whole life spent in traffic.
I like that they keep following up on the Face of Boe/New Earth story that started with rose and the Ninth Doctor watching the world end.
I really liked the Daleks in Manhatten storyline. Kind of tragic but it was nice that the Doctor was willing to forget all of his hatred in order to give his enemy a chance to be something better.
I loved the Family of Blood arc too. The Doctor's diary was neat, and I liked how in the end it turned out that he wasn't afraid of them but was hiding until they died as an act of mercy. I thought his punishment had a great ironic twist but the idea of the girl in the mirror will probably freak me out late one night when I go to the bathroom and see the slightest movement in the mirror.

I have several Tom Baker DVDs waiting for me at the library. Hopefully I'll enjoy those.

Bow ties are coool.