When approaching a classic like this, I'm always a bit apprehensive at first. I fear it won't be accessible, or that I won't "get" what makes it so timeless. With Of Mice and Men, this didn't happen. The little novella gripped me from the start. Sure, the dialect is heavy, but the rural setting, George's energies and Lenny's innocence (and sheer, abject, heartbreaking stupidity) instantly created an emotional connection for me.
I'm not sure whether or not this is a spoiler, but the end is not a happy one. A poignant, short classic I'm happy to have read.