This book begins very well, perfectly capturing the original Tardis crew and the feel and atmosphere of the early William Hartnell period. The whimsical subtleties of the First Doctor's dialogue and behaviour are superbly characterised with Barbara, Susan and Ian naturally falling into their usual roles around him. Unfortunately, after this great start, things begin to go downhill.
The novel soon slips into an atypical, common and fairly dull plot involving a civilisation trying to escape its imminent destruction in a massive impractical ship incapable of transporting to freedom hardly any of the population. It isn't the most original idea and it isn't very well realised here. It would have probably been a lot better if the Doctor went on to play a more proactive role in the plot. He is, for the most part, incidental to events. His aid is minimal and his concern more with the Tardis, its key and his missing companions. He even comes over a little blasé about the fate of Arkhaven and its people at times. But then there were occasional moments in the First Doctor's first year within the programme where he behaved a little like this. So perhaps the author has grasped this accurately as well. I just prefer the Doctor to be more relevant to the plot.
The three companions are generally swept along with events as well. For the first half of the adventure Ian is quite a proactive force, dominating his scenes. Half way through the novel, however, the author seems to run out of ideas for his involvement and he generally hangs around by the Doctor's shoulder worrying about Barbara. Susan, despite some time unconscious during events, is given a sizeable role due to the two parts she is effectively given and provided with plenty to do. Barbara spends a lot of her time trapped or escaping (this being quite common in Doctor Who) but her reactions and responses to situations appear genuine and perfectly in character with her TV persona. Her last line is also suitably ironic considering that this book is supposed to occur before, `Planet of Giants'.
The other characters of the book aren't very memorable though. They might vary between politicians, medics, rebels, teenagers and religious fanatics but they are all quite two dimensional and what you might expect. Even Monitor is your average computer gone rogue after achieving some level of self-awareness. There is also a seemingly unnecessary attempt to add some alien/monster threat to the story by using the Taklarians. They add nothing really to the plot and could easily have been omitted.
There are some nice personal scenes and some well written sequences though. The story just lacks any gripping quality and the characterisation is often quite flat when not dealing with the Tardis crew. It's a story that could be fitted into many science fiction series' and feels a little too generic.