Pretty meh. Most of the puzzles turn on some ridiculous gimmick that no one but the author would ever think of, and the ones which don't are dumb. (The most offensive one being the final stolen-recipe one, which is the worst 'locked room' mystery I've ever read - a recipe is stolen from a woman while she babysits a house of children. 'I bet it was one of the kids', I thought a third of the way through. It was. Even Isaac Asimov's reputation couldn't get some of these stinkers published before!)

The only two I'd call actually good is "The Four-Leaf Clover" for its interesting little debate about exploiting the superstitious, and "Unique Is Where You Find It", where Asimov shows off his knowledge of the periodic table by describing how almost every element has some way in which it can be considered unique (if he left out any, well, presumably that element is unique in being non-unique)!, which would make a nice little essay in its own right related to Occam's razor & the underdetermination of theories by data.

(Copies are available online. Download, don't spend good money on this.)