I I don't read police procedurals very often, although it's a genre I like - there's only so much serial killing and depravity I can take at any one time.
But when I do pick one up, it's always good to know, when done, that it was a good one. The Blue Hour
is, objectively, probably pretty middle-of-the-road, not particularly outstanding, but it was competently written, gave some nice characterisation and a reasonably intriguing plot where not all the threads were obvious until the very end.
Plus I liked the subdued, slow-burning romance between the two protagonists - spotting the book on a list with age gap romances was my main motivation for buying it, really, and it didn't disappoint, even though it was never at the forefront. I did wish the ending had been a little cheerier, but it made sense, plot-wise, and the entire book was really building up to it.