Fantastic and fun adventure with lots of flavor.
It might seem like you need the Doomed Forgotten Realms Gazetteer, but it is really unnecessary, only being useful if the players decide to go off the obvious rails and join an evil faction or look at the other locations in more depth.
In fact, the subclasses you get from the Gazetter don't really mesh a whole lot with this adventure, such as the wizard dedicated to exploiting vulnerabilities in a module with only one enemy that has vulnerabilities. So you probably won't be using a lot from it anyways, even if it does flesh out all the lore.
Formatting and descriptions are incredibly wonky, and it might take a couple of read-throughs to understand what it's trying to say or where things are in relation to each other, but overall it does the job of "Sword Coast, but everything is awful, and you are the world's last hope" thing incredibly well.