Overall I quite like this story. However I will start this review with some of it's negative points:
The story has a low budget feel and feels a bit rushed in places. One of the effects sequences involving a cracked wall in episode three has gone down in Doctor Who history for being a bit shoddy. This is a fair point I suppose. Also, the story does have a B-movie feel at times and some people may argue that the series has dropped in quality after the highs of the Philip Hinchcliffe era. Of course, this was the start of Graham Williams' time as producer. Perhaps a change in style/tone was inevitable.
However I must admit that I do find the story generally entertaining. Tom Baker is on fine form and we are introduced to K9. The model sequences in this story look pretty good and the incidental music from Dudley Simpson compliments the story well. The basis of the story uses elements from the 1966 sci-fi movie 'Fantastic Voyage'. Obviously Doctor Who's budget was a limiting factor but I feel the story is done reasonbly well.
