I wasn't fond of Girl in the Fireplace, tbh...it seemed like a very well written original story that had Doctor Who shoehorned in and most of the chars acting very OOC, especially the Doctor.
I LOVED School Reunion and New Earth. The wonderfulness of Elizabeth Sladen and Anthony Stewart Head were pure awesome.
I disagree with the idea of the characters acting out of character. The Doctor had recently regenerated, and in my opinion didn't have a character yet. In fact, I'd go so far as to say that the Tenth Doctor's character became finally stable and solid in
Girl in the Fireplace; the stories prior to it were wishy-washy in both concept and execution - particularly
New Earth. I felt it was tossed together, and the actors themselves didn't seem able to work off each other at all, especially Billie Piper while playing Cassandra-in-Rose and Matron Casp.