Just finished a full read of chapters 1 and 2. Chapter 2, The Dessarin Valley, Is awesome. Really excellent detail, plenty of npc notes location notes towns inn's etc etc I have a feeling that I will be referring back to this module for years and running adventures in this area well beyond whats published in this adventure. This module will be sitting in the forgotten realms reference shelf in my library for good I think.
For reference this module is set in 1491 DR - The year of the Scarlet Witch
Doing a quick scan through the book looking for monsters not in the basic package.
Scout - MM only
Veteran - MM only
Ankheg - MM only
Merrow - MM only
Jackelware - MM only
that's 3 pages looked over and found 5 monsters already so yes MM is needed
Maybe a web extra will be published to give the needed stats.