I enjoyed the BDHH. It is obvious that the BDHH was written by fans of Firefly and the Serenity RPG (SRPG).
The BDHH was packed with useful, practical information on how to enhance the SRPG experience.
The BDHH was actually equally designed for players and for the aspiring GM.
It has some clarifications on rules for the SRPG, but mostly the BDHH has a series of optional new gaming and meta-gaming material to supplement the SRPG. For example, there are sections on creating hero backgrounds, how the party meets, creating scenarios, and the obligatory section on new skills, talents, complications, etc.
There are also portions on how to make the SRPG more compatible with the evolving Cortex(tm) RPG system. This is the root system that the SRPG is based on, similar to the OGL for d20 or Chaosium's Basic RPG system.
If you liked the SRPG system and are looking for ways to expand it then you will also like the BDHH. That said, truth in lending, the BDHH is in no way, shape, or form necessary for playing, enjoying, or participating in many a varied and fun SRPG campaign.
If you liked Firefly and the Serenity movie and this is going to be your first purchase in the world of SRPG then I would just pull my hat down and mosey on to buying something else.
In service,
Rich