I think there are very few books of his I haven't read. "Letters to Malcolm - Chiefly on Prayer" comes to mind, but other than that, I think I've read them all.
I don't find his style to be dry at all, merely dated. He was a product of his times, but in his day, he was considered a sort of "Everyman's" theologian, very good at translating technical concepts into the language of the people. Sadly, we are not those sorts of people anymore.
People wanting a fiction recommendation would do well to check out 'Til We Have Faces. It is similar to Narnia in some ways (not too much), but more of an adult story. It is his retelling of the Greek myth of Cupid and Psyche. For nonfiction, The Four Loves is an under appreciated classic IMO.