I'm pretty much w/Chuck on this, except that I still enjoy the work of the "original" Mothers (up to and including the Burnt Weenie-era large group). But ti seems to me that the inability of that band to break through brought Zappa's cynicism to the fore and that it then became the main element of even his most "serious" work. And that just does not appeal to me.
Frustration's a bitch, I know, but...