JACS has provided, without a doubt, the most rewarding experience I have had while studying Japanese. The atmosphere is relaxing, the instructors are superb, and the course of instruction can be tailored to the student's specific needs. My wife and daughter also took some classes and have shared the same reaction; the experience was extremely enjoyable and very beneficial. The instructional materials are outstanding, and are presented in a way that ensures maximum retention without requiring boring drills or recitations.
I would highly recommend JACS Institute for foreigners of any level of proficiency.