Why the ending fails (SPOILER ALERT)
John Huston was 78 when this movie was filmed - it's always sad to see a once-great director helming a movie decades after he's lost the touch.
*SPOILER ALERT*SPOILER ALERT* But the main failing with Prizzi's Honor is the ending. It begins with the scene where Charley Partanna, his father, and the Prizzi's are discussing how to solve their dire problem. They agree on a plan. And the rest of the movie unfolds exactly as planned.
That is why the ending fails. In movies, when you see a plan for, say, a bank heist, hatched and discussed in detail, you can be certain that somehow things will go awry. It is the essence of entertainment - the unexpected; the way in which the best laid schemes gang aft aglay. What actually happens as opposed to what we thought was going to happen.
In the absence of that surprise, that twist, the ending becomes a letdown. I'm not sure which way the movie should have gone (after all, Ms Walker did shoot an innocent bystander). But the ending failed to save a movie which, at that point, desperately needed saving.