Mine is 380 pages (492 on Kindle), Hartmann's about 5,500. Mine is in English, his in German. Mine is postmodern, his (as best I can see) far more modern. There is, however, a particularly interesting commonality. Without either of us having known of the other, both Hartmann and I have been fascinated by the philosophers Wilhelm Kamlah and Paul Lorenzen. One may find further details of Hartmann's work at Neues System.
Hartmann's publisher Brill defines a metaphysics as "the philosophical treatment of the whole". I have defined it as "a grand unified philosophy, which integrates—or provides a means to integrate—all fields of knowledge and experience using familiar philosophical concepts". Purists might say that metaphysics is ontology: "the study of the nature of reality or what sorts of things are real". But this covers the reality of all kinds of things, which is to say, it is very broad.