How does one rate a crossword puzzle as Easy, Medium or Complex?
Complexity is tough to measure objectively for something as nuanced as cryptic crosswords. Apart from the clues themselves, the solver's ease with the crossword depends on many other factors.
Take natural flair for certain clue types. Some of us are have a knack for cryptic definitions, for example, others find them impossibly tough. A puzzle that's heavy on cryptic definitions will be easy for one and difficult for the other. Similarly, clues that require specialized knowledge are easy for those who work in those domains.
Familiarity with the setter's style also makes a difference. From solving a series of puzzles by the same setter, we learn little details about what to expect. Wordiness of clues, "noise" (connector words) content, style of surface reading, vocabulary, contemporary or old-fashioned references - different setters have their own quirks and the solver finds crosswords easier when he gets attuned to those quirks.
A solver calls a puzzle Complex if his speed or percentage completion with it does not match up to his personal average. If a community of regular solvers meet with the same result, we can then perhaps make a definitive statement about the puzzle's complexity.
But all that is in retrospect, after the puzzle has been solved. Are there parameters that can identify the difficulty level of a crossword before it is published, as it is done with Sudoku puzzles? I have been thinking of the varying complexity of puzzles published in The Hindu of late. Crossword numbers 9361 and 9362 were tough by The Hindu standards - completing them took me twice the time I normally spend on The Hindu puzzle. I thought why, and have some ideas. Will write more about it in a couple of days.
On a related note, here are a couple of articles from the Guardian's crossword editor about puzzle complexity:
Related Post: Does Length Of Clue Affect Its Complexity?