For example, after a few days my internal monologue petered out and for the first time I realized that a good portion of my mental activity was normally devoted to thinking about things I was going to say later on. Once I was out of the habit of talking all the time, I stopped cooking up little quips and observations about everything and really felt an expansion of non-verbal thinking.
So, although I had my doubts about the place going in, I left feeling that 10 days of intense internal focus was the only possible way to reach the insights I'd had, and that I was glad I'd done it. The months afterwards (while I kept up the practice, before I got "too busy"), were the most contented of my life.
If you want to know more about the Goenka approach, there are a couple of really good podcasts from Buddhist Geeks:
http://www.buddhistgeeks.com/2007/07/bg-028-entrepregurus-an...
http://www.buddhistgeeks.com/2007/07/bg-029-mass-producing-m...
I think they're pretty much dead on in their analysis.
While no one knows the triggers to these things I would _not_ recommend just jumping in because you thought it'd be cool! Read up, do your research, and do lots of smaller practice before trying.
That'd be my recommendation anyway ;)
Personally I find that the reasoning behind these rules is very practical. You see, the course is all about understanding what sensations are and the effects that they have in our psyche. So one of the goals is to limit as much as possible all sources of sensations so that you can easily focus on a few and see how the mind reacts to them.
I've been there twice in the past three years. I thought that I understood everything the first time. Boy, was I wrong.
[1] http://www.dhamma.org/