Has anyone or their kids read these?

So far I have only read books 1 and 2. I liked them. I am quite liking reading middle grade books at the moment. They are a fast read but some (particularly ones like these) are really interesting.

They are meant to be middle grade but are quite dark and twisted so I read online that many people would class them as 14 or 15 years +. Because of that, I read them first to decide if DD could read them. She has read some relatively dark things before (e.g., The Song From Somewhere Else and The Imaginary by A. F. Harrold) but there is something about The Riverman books that has a slightly more mature and scary edge to it. Maybe because the fantasy stuff is blended in with very normal everyday kid stuff that just seems very real. Or that the kids are doing things that are more like what kids their age could actually be getting into that are not mentioned in other middle grade books I have read. There is talk about smoking, alcohol, guns, relationships etc. But I think that these are things that would be encountered at an earlier age than 14/15 + these days, and its better to read them in a book and have discussions about choices and consequences than encounter them in a peer pressure situation.

I gave them to DD to read. She has not got round to it yet as she is in the midst of some other reading. She said she tried the first one but it was confusing and she would go back to it later.