At the start of The Second Doctor's tenure, someone high up decided that 4-parters weren't worth it, and that the production teams should focus of stories with 6+ parts where possible. That, as you may know, is a sentiment which didn't stick, and stories like this are exactly the reason why.
It is long, drawn-out and boring having only enough story for 4 parts.
The only notable thing about it is that it introduced the Ice Warriors and the only thing which I found interesting about it was Peter Barkworth's performance as a man who is half machine.
That is, for the first 5 parts, small change, just a short 2-and-a-half-hours!! But after you have battled your way through those five parts (my record is somewhere in the vicinity of 4 months) you are treated to a lovely bit of Doccy Who, with action and spectacle, for the time. Stakes and consequences, tension and release, the good stuff, shame the rest of it is so boring.
Also, side-note, the scientist's costumes are fantastic, the Ice Warrior talking effect is horrible and the computer is unintelligible.

4/10