Quite a nice brisk read. Roberts has got the interplay between Rommana and the 4th Doctor down pretty well. It was easy to envision Lalla Ward and Tom Baker in my head when reading the book. Its a fairly straight forward 'adaption' of the original tv script, and I'm really glad Roberts did not go the route some other authors may have and tried to emulate Douglas Adams writing style, and he pretty much stuck to his own. It is littered throughout with little tips-of-the-hat though, but they are not obtrusive and fit in enough so they do not draw huge red arrows that say 'Aren't I being clever here'.
Given the bare bones of what a TV script is (story wise I suppose) Roberts really expanded it very well. As well as the nods to Adams, there are the usual little bits of a New Adventures/BBC Books author here and there as well (added bonuses I guess. heh).