I liked it. It made me laugh out loud, which is a feat -- SPOILERS --
I enjoyed all of the characters. They all touched me and I could relate to all of them. I especially liked Jessica Tandy and Sylvia Sidney.
I thought Marcia Gay's character was a bit strange and her experience with the psychiatrist could have been elaborated or expanded, particularly since it was such a serious issue with her son.
Plotwise, it stretched the realm of believability, which is probably why the critics panned it. So, don't watch it for plausibility, just enjoy the interaction of the characters.
I didn't see Moonstruck, so I can't address the similarities or differences, but I did enjoy it.
I had to think long and hard as to whether I was offended by the scary lady in the black lace mantilla that frightened the toddler -- twice. I'm not as upset as I was when I first saw the movie, yet, I'm not really comfortable about laughing at the scene. I totally related to the toddler's reaction, but the woman that he was reacting to, I am just disquieted about it.