Finished this one last night and LOVED it! I wasn't expecting to enjoy it so much! Right from the beginning, I love the tone that's set. Everyone's on tender hooks as the UFO approaches. That was a lot of fun to watch. Then the feeling of genuine threat to planet earth was maintained throughout the story and was very exciting.
Everyone was great in this story. Even the guest characters had quite a bit of depth to them; I enjoyed scenes with Filer and the MP from the Ministry of Defence. I loved the power struggle between him and the Brigadier, too.
I feel like we didn't get to see the Master all that much in the first half of this one, which I didn't mind because his scenes in the second half certainly made up for it. Watching him pair up with UNIT and then the Doctor was a delight to see indeed. Loved it!
Also, since I am watching these stories in a back-to-back marathon, it's been weeks since I've heard the TARDIS take-off/land. It was actually very nice to hear it again in this story!
I really enjoyed this one. 5 stars from me!