Which might sound weird to anyone who's read Ubume no Natsu or watched Mouryou no Hako. While I do recommend taking a look at both of those series before embarking on Hyakki Tsurezurebukuro (being dropped right into the middle of the madness that is this manga might put you off the entire saga otherwise), it should be kept in mind that, as the central characters in this spin-off are the highly eccentric Enokizu and Chuuzenji, it's more entertaining and very different in mood and tone compared to the parent series: which, being narrated by a mentally ill horror novelist with a very grim outlook towards life, is dark, foreboding, and deals with particularly gruesome cases of rape, torture and murder.
Hyakki Tsurezurebukuro, on the other hand, focuses on more mundane crimes (robbery, forgery, extortion, coercion, etc.), and we follow the colourful cast of characters associated with the Rose Cross Detective Agency on their various exploits trying to obtain justice for the wronged and the powerless. Enokizu Reijirou is someone who puts even the more audacious interpretations of Sherlock Holmes to shame in the "eccentric private-eye" department, and Chuuzenji's surly know-it-all attitude might be off-putting at first, but once you get used to it you'll come to appreciate the fresh outlook on detective fiction that you can gain through a rich spoiled brat playing at "psychic sleuth" and a bossy, reluctant - but ultimately relenting - modern-day onmyouji in a world where the supernatural is a result of human beings' collective superstitions, prejudices and delusions rather than the work of otherworldly beings or energies.
But it's essential to have a curiosity for, and appreciation towards, Japanese culture, its myths and its religious beliefs if you're to enjoy this at all. If you really don't care one way or the other, and are averse to reading up on these aspects of Eastern society (the scanlator, shikiganai, is incredibly thoughtful in this regard and provides all the necessary footnotes), I doubt you'd enjoy any of Kyougoku Natsuhiko's works.
Tl; dr -- Recommended for fans of the main story; especially those who wanted to see more of Enokizu, who's a secondary character there. If you're unfamiliar with the original Kyougokudou novels or their adaptations, however, you may want to look into them first -- some of them do have English translations available.