The first three books in the sage were, in my opinion, extremely readable and enjoyable. 'The Tangle Box' (book four of the series) was an imaginative and gripping bit of fantasy, by far the best of the four.
Unfortunately 'The Witches Brew' was somewhat off the mark whilst, to me, 'A Princess of Landover' (book six of the saga) shows that Mr Brooks has stretched a good idea far beyond its natural breaking point. And, sadly, the ending of this latest offering suggests that a sequel isn't far away.
Read and enjoy the first four books in the series. Don't expect too much from the last pair and, when it is listed, be a little cautious before pre-ordering the sequel to 'A Princess of Landover'. Wait for some reviews.