Grapes is totally ham-fisted. The politics and the clumsy Christian themes and parallels drove me bonkers. I would have rather read a ten page essay on his political views than slogged through that book. I hated almost all of the characters, as well.
I even switched to the audio-book halfway through because I didn't want to give up.
Worst ending of any book I've ever read. What. The. Hey.
I didn't read fiction for 8 months after Grapes.
Steinbeck managed to write both my least favorite book (Grapes) and one of my favorites (East of Eden). East of Eden is not perfect but I really loved reading it.