When I first read 'The Eyre Affair' I thought that is Fforde was one of the most original writers out there, even though his whole concept was an expanded riff on Woody Allen's classic short story "The Kugelmas Episode" from the 1980s.
However, the quality of each addition volume in the Thursday Next series declines expontentially. The last one was nearly unreadable.
Also, the more books I read from authors like Robert Rankin, who was writing years before Fforde, the easier it is to tell that Fforde essentially is simply trying to outdo Pterry, Rankin, Adams and other fantasy/far-fetched fiction actions in originality and cleverness, and in some cases rips them off entirely.
For example, when I ready "The Big Over Easy," published in 2005, I thought it was one of his best and most original books in years--far better than all of the sequels to "Eyre Affair." (Its sequel, The Fourth Bear, is horrible).
Then, last year, I read Rankin's Hollow Chocolate Bunnies of the Apocalypse, published in 2003, which had a nearly identical plot and used many of the same nursery rhyme characters.
From there it became quite apparent that Fforde had based his story on Rankin's.
Which basically has led me to the conclusion that while on the surface Fforde seems very clever and original, he really has very little to offer in terms of truly original ideas, and those that he had were all spent in full in The Eyre Affair. Everything that has followed, for me at least, has been increasingly plodding, overwritten, and unoriginal.
But, as they say, YMMV.