Not just for children!
Reading children's books can play an important role in learning or improving your English language skills. Don't underestimate the amount of new vocabulary you can discover while reading these "simple" books.
Dr. Seuss books used to be my favorite books to read! Reading Dr. Seuss books to my children was a great way of teaching them how to talk. Children pick up quite a bit of vocabulary very quickly when being read to. That is also an easy transition to teaching children how to read. I highly recommend reading Dr. Seuss books for improving the language skills of adults as well as children.