C’mon everybody give it up. Ye simpletons need to move onto more adult puzzlers. Diagramless crosswords are a good start. Cryptograms are also interesting and difficult. But the greatest of all these are Acrostics (sometimes called Crostics or Anacrostics).  Infinite enjoyment. Solve a Bertrand Russell quote using the letters to solutions of complex crossword clues. Although there are a set of axioms that can be applied to solving any crostic, there is no grindout solution like Sudoku. It requires intuitiveness, vast knowledge of every aspect of life (arts, TV, history, geography, etc. etc.) and the ability to work off the quote to solve the clues and vice-versa. In summary, you need to be smart. Sudoku-ites need not be smart. They need only stick-to-it-iveness and practice. I think even a chimpanzee could solve those things (well, maybe a thousand chimpanzees on a thousand computers).
Sudoku is to pencil puzzles as Dan Brown is to novelists.