The only original content not already in the base game is a few comic book pages between missions. Entire buildings are copy pasted from the main campaign but you'll enter them through a different door. Zero continuity from Episode 0 beyond character abilities and perks you have no chance in hell of maxing out.

1/10 this should be free because you've already paid for everything

Shockingly bad

You can eat Nazi dog food GOTY/10