I never watched the newest incarnation of Doctor Who in 2005 until recently, but I finally got hooked. I really liked Christopher Eccleston, but David Tennant's performance was awesome as "The Doctor." He was whimsical and brilliant and at the same time he also connected to the inner sadness and helplessness that came with being a powerful Time Lord.
Losing the people he loved was almost too much for him to take and it manifested itself in the episode called: The Waters of Mars. It set him on a course that he couldn't come back from.
Anyway, Matt Smith and Karen Gillan take over as the new duo that travel through time and space with the help of Steven Moffat, who takes over for Russel T. Davies as the lead writer and executive producer of the show.
(PS, I love Torchwood too....)