We have been using SL for 3 years. My children have much enjoyed the way history is taught. They have learned more in core 1 and 2 than I think I learned in my entire schooling career.
I really have struggled about switching to something else that follows the 4 year cycle, but when I sit and make out my pro and con list, SL is a gem for us. We love the literature approach, and it works for us.