I'm currently reading this as a textbook for a linguistics class and I REALLY like it. (If anything ever qualified me as being a nerd, it's that last statement.) It's written in a clear, accessible manner that makes it almost possible for me to understand the abstract concepts of linguistics and SLA research.
Found the mix of theoretical overviews, in-depth research articles, and workbook like activities or tasks to be very novel. More books like this please!!