The animation is atrocious, the acting is sub-par, the story is incredibly simple and predictable, and it's not worth the 42 minutes of your life you'll spend watching it.

All that said, though, there are a few good bits. I like the design of the Viperox and the Skorpius flies. There are a handful of references to Doctor Who canon, which are always fun. Tennant's acting is great (as always), and he gives a handful of good speeches.