I had kind of a weird reaction to this one. Best I can assess, I think that to me it didn't feel like a Doctor Who story. Which is weird - it has the Doctor, Jo, the UNIT gang, aliens...and really, there are elements that fit the UNIT years perfectly.

So, why doesn't it feel like a Doctor Who story? I'm not sure. Maybe it's the aspect of (apparently) shifting loyalties, or maybe it's the Doctor and Jo going on the run. Possibly it's that the aliens, with their weird heads and all, are pretty close to superfluous to the story. You could just about skip them and make the plot device some human-invented technology. In any case, it feels more like something out of the Lethbridge-Stewart line than something out of the Pertwee years of Doctor Who. It also put me in mind of Three Days of the Condor a little bit.

But is this a good thing or a bad thing. I wouldn't classify it as either, but it did keep me interested, and for a release over three hours in length, that's not a small accomplishment.