Great production values in this one. Love the costumes/uniforms, the model work was very good, the Wirrn was a great creation, and the sets were beyond amazing - particularly the windowed corridor and the crew's stasis chamber. They got good use out of the sets too, as they were used for Revenge of the Cybermen as well.
One drawback was the use of spray painting bubble wrap green for the transformation of Noah, but its still kind of effective.
The story itself is a cracking good one with lots of great moments for Sarah and Harry.
A classic and essential viewing.