The interviewer claims to have been an obsessive SF fan from early childhood. As such, he should have been able to ask pertinent questions from his own knowledge. This did not really happen as he was aiming to sell the interviews to a non-SF market. The consequence is that it this little book does not go very deep. For example, he fails to ask Fred Pohl about his collaborations, or any of his fifties work, or why he spent so much time as an editor when it wasn't as profitable as his own writing. Despite that, this is worth having, particularly at the price. The Frank Herbert interview is the only one to include the published article, which is as useless as all the newspaper articles I read about SF authors at the time, and, frankly, later.
The Pohl interview is as engaging as any other of the many interviews with him, and no more deep. The two with Simak reveal more about Simak's personal life than his works, and reveal his modesty and sense of isolation.
The raw interviews with Herbert and Dickson are the most interesting, not in facts, which are relatively sparse, but in personality. Both are egomaniacs and very satisfied with their works. Both, particularly Dickson, run off at length from the bland questions asked. This inflated view is certainly not unusual from major SF authors of their generation.
So, not an important work, but an example of how the modest costs of e publishing allows the publification of marginal books.