I liked Learning Spanish Like Crazy, but it may not be for everyone. It is to a large degree an audio instruction course. Depending on how you learn, this can be a big plus or a big minus. I personally am a very visual learner and written materials are a big help for me. Some people find written materials a hindrance.
If you comute a lot and/or are used to learning via audio tapes, podcasts, cds etc etc, this may be your ticket. I find it difficult to really focus and learn while I am driving but I have several friends who have darn near earned college degrees by this method.
Learn Spanish Like Crazy
There is a lot of information packed into each lesson. So much so that it is not realistic for someone to learn it all by listening to it once. More than one, or even several reviews of each lesson is probably necessary. Again, this is not necessarily a bad thing. But some people can become over-whelmed or discouraged by this fact, prefering individual lessons containing less information so they are able to take in and process it in one sitting and then moving on to the next.
I am going to generalize and say that for the very beginner this may not be the best course, only because I think some written materials are necessary at that level to get the basics. Basic verb conjugation can be made much easier to learn initially with at least a some visual aids.
But for the intermediate learner with some basic verb and vocabulary knowledge, I think this is an excellent course. It is very cost effective compared to some of the better known courses (pimsleur for example), but is as effective or better at advancing the student who has at least a little knowledge.
It does also carry a money back guarantee.