I bought this some time ago and forgot to come back and say something about it.

If you are looking for a medicinal reference or a collection of herbs all set up for a specific game system, you won't appreciate this collection of herbs at all. If, on the other hand, you are looking for a collection of herbs with notes on how they were used and some folklore references to more fantastical properties so that you can incorporate the herbs as you see fit in any system, then you will appreciate this collection. I think it was well done, and am definitely incorporating aspects inspired from this into my games.

"Whistlestop Guide to Herbs" is a guide to herbs from the British Isles, where they grow, and what they have been used to treat or mis-treat.

It isn't a medical reference, and doesn't discuss dosage, effectiveness, counterindications, etc. For example, for most people, mint, basil, etc. improve digestion, but for some people, they can worsen digestion and trigger vomiting.

It doesn't include rules for treating symptoms.

It should help roleplay treating symptoms, in pre-Industrial campaigns, especially in the British Isles or elsewhere in Northern Europe.

It doesn't help roleplay poisoning, or investigating poisonings, especially since it omits deadly nightshade and foxglove.

It would be nice to include more herbs, from more regions, and to include more information about rarity, taste, effects, and side-effects.

A 17 page (plus cover) booklet giving brief descriptions of real-world European herbs, and the sort of things herbalists thought they were useful for. 47 herbs are listed, each with a short entry describing its appearance and where you can find it, and one or two sentences on its uses. It's nicely laid out, with good line drawings of most of the herbs. It's usefulness in game is, however, somewhat questionable, except maybe as inspiration for potion ingredients or something, or if you're playing a low-magic game with a herbalist PC.