I enjoyed the Song of the Lioness quartet quite a bit. If I had read the books when I was at the target age, they probably would have been among my favorites. As an adult, and a writer, I find them good, but not great.
Alanna is a likeable hero. She is not perfect, but she tries and is (mostly) able to admit her mistakes.
Pierce is most at home when writing action scenes. When in the midst of a fight, the reader is right there in the middle of the action, feeling every punch and clash of the swords.