I'm using this currently in a Blueholme (Holmes Basic retroclone) campaign and it is perfect. I can't recommend this enough!

I love this game. I've got two 5e D&D campaigns that I'm currently running and have been looking for a way to introduce more old-school play to my group. This may do just the trick. When my current games are over I'm thinking of using to either run Rime of the Frostmaiden or one of the Goodman Games Original Adventures Reincarnated series. I'll say more about it once I've run it, but from an initial read through it is a very exciting marriage of the best features of old school games with modern mechanics.

The print production quality is my only complaint. I wish it were available as saddle-stitched booklets rather than perfect bound. As it is the text really crowds the center margins at the spine of the book making it a little bit of a strain to read. But the content is good enough that it is worth the minor annoyance and if it became available in saddle-stitched booklets I would buy it all over again.