On one hand, there are moments of memorably daffy invention here, more than I would expect from the studio behind Trolls.
On the other hand, so little of the story makes sense, and that Glengarry Glen Ross reference is unearned and stupid.
The Despicable Me franchise--really, the entirety of Illumination Entertainment--thrives primarily because people are willing to shrug and give a lazy movie a pass because, to quote the old hula-hoop inventor, it's...y'know, for kids. As if being...y'know, for kids is a free pass to condescend to children as a sort of lowest common denominator.
So, big surprise: Despicable Me 3 is as lazy and rote as a Very Special Episode of Season 11 of a sitcom that still gets very high ratings in spite of not being very funny. My review at Slashfilm goes into more detail.