Developed by Green Ronin Publishing this module is the next in the DND 5th edition lineup
The first thing I noticed with this book was the very high price. 64$ in Canada and 50$ in the usa, Yet some online sellers have it for almost half that. A bit more of an investment but if it gives enough play value it should be worth it.
Print quality is excellent and the images within are top notch and the maps are beautiful. A considerable amount of space in this book deals with setting of the underdark beneath the western heartlands and specific locals within including towns and cities so as a source book its quite useful as well as the actual adventure within. Ruels for dealing with madness levels and 2 pages dedicated to "fungi of the underdark" expand the page count and do cut into the actual adventure space.
The adventure beginning is an interesting one starting the party at 1st level in the slave pens of the drow.
By chapter 8 the party will have adventured through a large area of the underdark and arrived in Gauntlgrym to deal with the king but with no maps and little detail I felt like a person who had not read all the novels dealing with this area would be a bit lost in running it.
The chapter on Menzoberranzan was especially rich on detail and light on adventure. The new monsters and magic items were very good.
Overall this book holds a lot of great information about setting but seems like it would take more GM prep time than most store bought modules. A full read through of chapters before the players arrive in them is critical in many cases as well as some internet research to fill in some knowledge holes.