Just finished the ebook.
Definitely one of the best HH books in recent memory for me. I can't rank all 36 since I haven't read the earlier ones in years. Looking at just book 20 (Primarchs) and up...I would say only Betrayer and Scars would be comparable in quality, in my humble opinion.
There are quite a few plot lines at the beginning but they converge nicely near the middle of the book.