Having enjoyable text to read/listen to that is just comprehensible enough to get you to keep working at it really a pleasurable way to learn a language. LLPSI is also great, and at times is a delightful read. I find myself also really enjoying Ørberg's student manual, in which he reveals (in English) all the finer points of the Grammar the text is trying to get you to internalize. It's amazing how much grammar you can just intuit by reading -- like I understood participles without explicitly realizing they had been introduced in Chapter 14.