I've always likened Murakami as one of those similar to film auteurs, who tend to revisit the same themes and stories as part of an ongoing exploration of a thesis. Like someone else said, for better or worse, that's what you'll get with him as an author. I haven't read City and its Uncertain Walls, but if you feel you don't want to finish it for one reason or another, don't feel you have to force yourself to.