This book is almost all sex, with just enough plot to keep the reader interested in the story. Harry is fucking Draco, and magically binds themselves together, essentially making Draco his concubine, his slave, Draco has to pretty much do everything Harry says. Oh, and if Harry doesn't fuck Draco every day, Draco dies.
The sex is off the charts hot, even if there is way too much of it. Draco and Harry fall in love, and things get rather sappy quite often, with a lot of "yours forever" "always" "mine", etc.
Harry being Harry, is trying his best NOT to compel Draco to do things against his will, so don't go thinking of this as him taking advantage or going to the dark side or anything, he's still very much Harry, doing things without thinking.
This is a long series, and I'm interested in the story, we'll see if I can keep up with it while skimming all the sex.