Cher plays Loretta Castorini, a widow in Brooklyn who gets engaged at the beginning of the movie to Johnny Cammareri (Danny Aiello) although it's clear that she doesn't love him. Johnny goes back to Sicily to attend to his dying mother, but requests Loretta invite his alienated brother Ronny (Nick Cage) to the wedding. Much humour ensues as Ronny and Loretta find passion together.
I was thoroughly unimpressed by the clichéd American-Italian acting - accents, hand-waving, adding "capisce?" to the end of sentences, fighting-because-we-love-each-other. This can be partly attributed to the movie being made in 1987, but that doesn't make it better. The whole thing is firmly stuck in parody and caricature from beginning to end. Despite the characters being drawn in incredibly broad strokes, Cher, Cage, and Olympia Dukakis (as Loretta's mother) manage to bring considerable charm to their characters. But when you bring caricatures and a limited story, you'd better be damn funny - and the humour didn't really work for me.
Rotten Tomatoes "Critical Consensus" (as of 2017-01) claims the movie is "Led by energetic performances from Nicolas Cage and Cher, Moonstruck is an exuberantly funny tribute to love and one of the decade's most appealing comedies." So I seem to be somewhat outvoted.