Review of all 4 parts:
This was the first story after the departure of Robert Holmes as script editor, following the recent exit of producer Phillip Hinchcliffe. Those two geniuses had created what I think is still the best era in the show's history. Holmes leaving was very sad for the show and that point is hammered home by this inadequate adventure. That is not clearly going to be the case in Part One as although it is below par compared to the great material the show had been producing, it was not too bad. Parts 2 and 3 though are extremely embarrassingly weak and Part 4 is not much better.
In the opening episode the TARDIS arrives on the Minyan ship, finding the crew are on an incredibly long quest. They face a meteorite storm and the Doctor tries to help. Everything at this stage is not that bad at all. The crew are not brilliant but are acted adequately well, the script is stodgy but reasonable, the setting is fine, the premise is OK while the effects are ambitious and actually pretty good for the time. The Doctor. Leela and K-9 are providing some charm and although the episode is not outstanding or impressive, it is acceptable.
Once the ship crashes into a planet at the start of Part 2 things go hugely downhill. The planet is poorly created with bad CSO effects due to lack of budget but no amount of CGI improvements could mask the real issues which are the direction, acting and script. Director Norman Stewart has failed miserably in the 2nd to 4th episodes with so many scenes badly directed, badly acted, badly edited and seeming like a poor amateur dramatics effort. The dialogue is poor but it is also delivered so badly and with so many mistakes in how actors carry out even the smallest physical actions like flicking switches, falling over or reacting to something that it makes me cringe. Action scenes are very weak but so are lots of minor interconnecting scenes with the Seers and workers from the planet. It is embarrassing. I guess the first part was so much better because it only had Tom Baker, Louise Jameson along with the ship's crew and K-9 plus a load of model shots. The director could not fail so badly with that material. But once we get the wider cast on the planet who are all rubbish actors he is unable to direct them to do anything well and he has failed to direct the CSO effects or action well at all also. Tom, Louise and John Leeson (as the voice of K-9) are fine and the ship's crew are not too bad but even they start getting worse. Part 2 and especially Part 3 are easily the worst Who episodes by far up to this point and would only be matched in their bad, pantomime style, silliness when the show reached its low point in Season 24.
Part 4 is not quite as bad but is still weak and it is only the presence of the Doctor and Leela that keep the middle parts from being even worse. Part 1 was not great but was so much better and is the only reason this is not challenging Delta and the Bannermen to be the worst TV episode of the show.
Writers Bob Maker and Dave Martin and producer Graham Williams deserve a fair portion of blame and new script editor Anthony Read was unable to make any positive impact but I feel the support cast and director Norman Stewart were especially at fault. Yes the budget was low but that does not excuse the lame scenes in Parts 2 to 4.
My ratings: Part 1 - 6.5/10, Part 2 - 2.5/10, Part 3 - 1.5/10, Part 4 - 3.5/10. Overall - 3.5/10.