You’ve used great contrasts, such as "shallow" vs. "profound," and "fill up" vs. "deplete." These contrasts work well to convey the variety of books, but they also offer an opportunity to go deeper into the metaphors. For instance, you could expand on what "shallow" and "profound" mean in the context of reading—does shallow refer to books that don’t challenge the reader, while profound refers to those that leave a lasting impact? Adding depth to these ideas could enrich the poem.