Ratzinger’s textbook on the last things is very strong on the debates swirling around the nature of the soul, the body-soul relationship, and the temporal aspects of eschatology. Purgatory is adequately treated and heaven inspires some of that fine Ratzingerian theological poetry, but hell is handled briefly and not in much depth. He seems to want to just get it out if the way. That said, it’s a good treatment of the subject, but probably not the introduction a novice should turn to.
Buy Eschatology by Joseph Ratzinger at Amazon.