There really was no need to open a new thread on this.
Have you tried looking for reviews in the academic journals when it was published? Google scholar (keywords: Schwyzer Grammatik review) is useful for this. Also, if you're associated with a university, try searching JSTOR.
What, in particular, are you looking for? For most purposes, I suspect Schwyzer, K-G or even Smyth would all meet your needs (i.e., I highly doubt any of them are missing large areas of grammar; the difference would probably in amount of detail), and if you need information on a specific subject (say particles or word order) you would be better off referring to a monograph on the subject in any case.
IPHIGENIE: Kann uns zum Vaterland die Fremde werden?
ARKAS: Und dir ist fremd das Vaterland geworden.
IPHIGENIE: Das ist's, warum mein blutend Herz nicht heilt.
(Goethe, Iphigenie auf Tauris)