I've been very pleased with this so far. The first box really sets the tone with a letter of premise (in-world "why you're getting these packages" description), a letter from the killer (vaguely hinting and suitably unsettling), an article, a journal for your notes (which is just beautiful btw), and some different items that don't quite seem to connect to each other yet, but that's part of the mystery to solve! There's also occasional e-mails to tide you over until the next box (and give you clues).
I'm very intrigued by where the story is going and I can't wait for the next one! I feel like the detective in a mystery novel.
I had subscribed with the Mystery genre subscription about a year ago, and this time I thought I'd try their Horror box. So far, I love it. I liked it before, but they really hit it out of the park with the Horror selections.
I love the different types of books that come from this subscription. They're all guaranteed vintage, and every one I've received has been great.