This was a mixed bag for me. I'm a big Dr. Who fan (obviously, why else would I read this?), so I've read the novels about him, Torchwood, and would read Sarah Jane if I knew of any. I've found the books to be hit or miss, and this had some of both.
The basic idea is that, after a mild disagreement about zoos, the Doctor tries to take Martha to see a dodo. They end up at the Museum of the Last Ones, a place dedicated to preserving the last member of any species. The Doctor isn't pleased with the place to start with, and less so the more they learn. Then it doesn't help matters any when they realize his status. There are a lot of surprises and twists along the way.
The writer nailed the Doctor as played by David Tenant. He was dead on perfect and I could see him doing the things in the book. There was a brief, temporary companion who was really well written and had a few entertaining moments. The villain made sense, and had a rationale for what they were doing.
Martha didn't feel quite right to me, I'm not sure why. And, as happens even on the show sometimes, the sonic screwdriver got a bit deus ex machina.
It's a decent read that should be fine for Dr. Who fans, especially of the Tenth Doctor.