I enjoyed it, but most of the truly funny moments (not all) were in the advertising campaign. I believe the joke of Nacho's physique was played out for me long before the director got tired of it
It is not a good thing for an individual's first film score to be rejected on any level. It looks like some of Beck's score did remain...but situations like this will only show the studios that composing music for a film is a much different talent than writing songs or composing an album. It looks like Elfman has taken a very professional "high road" approach to his involvement in the film and has not allowed the spotlight to only shine on him by not taking the "music by" credit that the studio offered to him...even though he did most of the movie.
That may be because Elfman's own career started in a similar manner (pop star turned film composer), though I've never heard of any of his scores getting rejected or "pared down".