Pardon me for joining in late. I enjoy a tough puzzle as much as anyone - but as I have to work for a living, I only have so much free time for puzzling. In a good week I complete three puzzles: Spectator, Azed and Mephisto. I like to do them in more or less that order because, for me, the Mephisto is usually the least enjoyable of the three.
I did manage to complete Mephisto 2604, but only by spending far too much time on it. (Cussedness may also have been an issue.) I felt it was too difficult for a Sunday crossword with a 7 day deadline; and that some of the clues were not really fair. Why should a solver assume that "Fred" refers to Mr Fred Dibnah? How can the word "grok" be justified if it does not appear in the dictionary most of us rely upon?
I look forward to retiring one day - and having the time to grapple with Paul McKenna's output. In the meantime, I may have to learn when to put a puzzle down - and that's something that goes against the grain.