Midnight in Paris was very good.
I know what you mean about the repetition. Pervasive in his works is a mistrust of academics and intellectuals, glorification of self-education, disillusionment with traditional relationship models, the city, classical and jazz culture, and so on.
I enjoy all these things though. I respect that he doesn't follow filmic trends, and just does his own thing. While he can be a bit hit and miss (especially in the last fifteen years), it's nice to have his familiar style to come home to after enjoying all the more progressive cinema elsewhere.
I didn't love Manhattan myself. It's good, but I can't really relate to it like I can with Annie Hall, or Hannah and Her Sisters.
I recommend one of his early collections of short stories. They're quite a bit more like his "early, funny films" in their surrealism, and well worth it. His more recent collection, Mere Anarchy, I thought was quite weak however.