I believe Magnus Mills to be a fine author, but this book left me unhappy and disatisfied with the way it had been published. It contains basic spelling and grammar errors, which should not get through proof-reading, let alone to publication.
The story themselves are good, short stories. You are able to get straight into the story with them, and as per his writing style, no time is wasted on description of areas, clothes or appearence. That is all left the imagination of the reader, which some will find unfulfilling, and some will not. I personally, do not and very much enjoy his writing style.
If you are really interested in reading his short stories, I would recommend buying his collection 'Screwtop Thompson'. This book contains all of the short stories from Once in a Blue Moon, and Only When the Sun Shines Brightly, but as it is a later edition of the book, the annoying errors have disappeared, making it a far more enjoyable experience.