The basic idea of Geist is great and opens up possibilities for cross-overs out of necessity: A player character dies and remains as a geist. You could use this for any of the WoD systems, although this possibility is only explicitely mentioned for ordinary humans. As such it is a great supplement. My criticque is a different one, it is the approach on Keys. In Geist you do not only have supernatural abilites, called Manifestations, but also Keys. Each key allows you to use a Manifestation slightly different. Well, this may sound cool in the first place, but in the consequence the writers lacked the idea to make keys all that different. So you may buy keys to individualize your Manifestations and most of them still remain so similar, it is just sad.
[2 of 5 Stars!]