So, Waterdeep: Dragon Heist is, at least in my opinion an amazing product for those who want some more deepth in their character creation. Pop this baby out at session 0 and character creation and you will easily have even the staunchest "plays the same character every time" traditionalists experimenting more than a bit. That at least is how I will use it, randomly distribute them and build haracters with that in mind, you could just as easily read some out to players or match them with their pre-made characters according to your own wicked DM heart.
The secrets range from subtle and engaging like owing money to certain npcs appearing in the adventure to amazing situations like being a polymorphed dragon, an intellect devourer or Volo having a restraining order against you (Psch, that hack would be lucky to have one of MY characters obsess over him, while Daerdan on another hand now that's a REAL author).
Overall give it a shot, it showcases the best parts of dnd 5th edition, it is simple, but can have a lot of depth, and a GM will have plenty of hooks to use in this relatively cheap PDF. At just over ten cents a hook, I find it more than worth its price. (Hell I paid fluff writers for a company webpage more per word. And trust me their quality was way worse.)