First up, I gotta say, this is one of the most pleasant art styles I've seen in any manga - not just Touhou manga. Props to Azuma Aya - there was never any moment in which your art was caught lacking across these wondrous 51 chapters.
(Speaking of 51 chapters, it's more like 56-57 due to many extra stories, and depending on what site you use the last chapter is sometimes split into 2 separate chapters)
Anyways, Wild and Horned Hermit is one of the best Touhou manga out there. It follows the same structure most Touhou manga follow, that is to say, two or three chapters in which an incident occurs that Reimu, Kasen and the gang have to solve. But within each of these stories, so so so so much depth was there, cultural allusions, Japanese history tenfold of any other Touhou manga. With close to 20 differing stories within this manga, it's absolutely incredible how literally NONE of them are boring at all - all of Gensokyo is incorporated naturally, sort of 'guest' appearances of smaller characters such as Aunn Komano, Ichirin Kumoi, Kogasa Tatara and etc appear frequently, truly showcasing the depth and care put into Wild and Horned Hermit.
There is a cool air of mystery to it too - as one who didn't know much about Kasen upon entering this adventure the constant mysterious references and actions Kasen pulls off all build mystery and tension to one of the most surprising and THE greatest ending in all of manga*.
I don't really want to say much else in case of spoilers, but please, PLEASE give Wild and Horned Hermit a try - 100% guarantee you'll love it as much as I did. If you don't, I'll make sure to get your money paid back**.
Enjoy!
*As always, subject to debate.
**Terms and conditions apply.