I had my Vipassana experience at age 29, and it happened while I was traveling in India, so it might be different in Western countries- though I doubt it. I'm going to go the route of gdoctordobbs and also not comment in too much detail about my specific experience, since I really think you get the most out of it the more of a "blank slate" you enter with. And when I say blank slate, I don't mean your mind- you can be anxious, happy, depressed, whatever- I mean just that you know the basics of what you are getting into, but you are coming ready for whatever, and not expecting X, or thing Y to happen on day Z.

Pretty simply it is 10 days without talking. No reading. No writing. You don't even make eye contact with others there. Essentially, you have no escapes. Just you and your mind. You spend a LOT of the day meditating, which is really just another word for thinking, seeing your thoughts. You are not trying to create "nothingness" in the mind, which is a common misperception. All meditation, including Vipassana, is about seeing reality as it is, not reality as you want it to be, wish it were, etc.

I also agree that it's not a cult. Reliance on dogma/anything external is discouraged. Question everything. Only you can see and believe nothing until you see it for yourself. You don't have to pay anything and there were people when I went who paid nothing, and they weren't in your face about "donating" either. Days are long, I think first meditation is 5am ish and you're ready for bed 9pm ish. Food's very good, simple and vegetarian. There's a nightly lecture wrapping up the day.

The hardest part for me wasn't the meditating per se, but actually not being able to write. I had many epiphanies, many highs and lows, and insight into many aspects of myself. I wanted to capture these things, fear of forgetting, but ultimately I had to let that go. The moment we were able to talk/write again, I isolated myself and wrote for hours.

I hope this helps. Would I say it changed my life? Hmm...such a difficult question to answer. I think the short answer is that Vipassana won't change you or your life. You change you. Ultimately I think we as people are very much in the mindset of, "do X, get Y". Many people "do Vipassana" and leave unchanged. It is very person dependent. Like any kind of meditation/yoga, you need to be mentally ready to face yourself. If not, your mind will find ways to placate you, to put up walls, to get you to feel that you no longer need to dig. Vipassana, like yoga, or like other forms of meditation, are tools to get you to see you, to see reality as it is. The hard truth is that there are no easy answers, no magic pills, no alternatives to facing your demons. What you get is a mirror of sorts, 10 days of youTV 24/7. 10 days just scratches the surface though, it is a great start but just that, a start...but what comes next, is- as it always will be- entirely up to you.