I can't believe it's actually taken me a month to finish this book, although in my defence I did work a lot, and it is a very long book. Each story varies between about 10-20 pages, but the complete collection weighs in at almost 800 pages.
I'm not normally a fan of short stories (the only collection I've really enjoyed is Michael Marshall Smith's What You Make It). My reason for disliking most is that they lack a sense of depth and continuity, the ability to get lost in them, which is my main motivation for reading fiction in general. The Father Brown Stories, however, obviously have continuity, because they're a set of stories about the same character. Each mini-mystery manages to set the scene so effectively that, even after 15 pages, you feel as though you've lived a full novel in the setting.
G K Chesterton also has a gift for pithy and amusing character description - a good example is:
He saw Dr Simon, a typical French scientist, with glasses, a pointed brown beard, and a forehead barred with those parallel wrinkles which are the penalty of superciliousness, since they come through constantly elevating the eyebrows. (from 'The Secret Garden')
His ability to effectively describe a character or place in one sentence in a way that really evokes them is what, for me, really sets these stories apart. The mysteries themselves vary in their complexity and convincingness, but are always solved with a wonderful sense of humanity and compassion. Most other detectives I remember reading about see the crime as a cold, set puzzle to be solved analytically and the criminal mercilessly packed off to gaol, if they haven't already been killed in some way. Father Brown, however, solves a crime by imagining the type of person who would do such a thing, putting himself in their place, and working from there. When he's discovered the criminal, he often lets them escape rather than dragging them in to face the full force of the law. He even converts a world-reknowned thief to the side of justice and remains fast friends with him throughout the series.
I wouldn't necessarily recommend reading the entire set of stories back-to-back (unfortunately I feel compelled to read books that way, but I'm not sure it's the way to get the best out of short story collections), but I'd definitely recommend them as something to dip into. Each story is atmospheric and the pervading sense of compassion gives a much more optimistic feel that that found in most detective stories.
Next up: The Eyre Affair, by Jasper Fforde