My first longish, strict retreat was a Goenka retreat in Hong Kong. Since I already had a Buddhist practice, had been to several weekend events with famous and not so famous teachers, and had studied quite a lot, I was a little puzzled by the insistence that it "wasn't Buddhism", since the Dhamma talks seems relatively standard (Noble Tuths, 8-fold Path, Dependent Origination, etc). Of course, they had their own unique spin, just as talks by various other teachers do... And, as with some other teachers, the insistence that this was "the pristine method of the Buddha" was a little grating. However, it was great to have a well-organised retreat where one could just get on with practice. I learned a lot from the experience, but soon returned to my usual (Mahasi-style) practice.
There were a couple of Westerners on the course who had been in China for some time studying Tai Chi and so on, so had their own, somewhat different practice. At the end of the course (when you get to talk), they expressed surprise about how much Buddhist doctrine there was in the talks!
Mike