Sounds a bit like a sect attempting to attract new drones.
Definitely not a cult. I've looked into it and the set up lacks the infrastructure to be a cult. They don't harangue you to give them money or to believe a certain scripture, etc. They also screen people out who would normally be the type that cults would find easy to subjugate, like those with mental problems. If you're being treated for anxiety and depression or substance abuse for instance, they weed you out in the application process. They aren't equipped to deal with such issues and are pretty serious about rejecting such candidates. Cults on the other hand love to pounce on people like this because they are usually in a weak and impressionable state.
It simply is a retreat focused on meditation taught by this guy Goenka (via video tapes) who believed it takes 10 days to really learn and advance in meditation. After you've "sat" for a 10 day retreat you can come back for 3-4 day (or less) meditation sessions. And from what I understand it's a lot of sitting around meditating. No talking, no socializing, no field trips, just waking up and sitting in a hall mediating. If instruction is needed you either glean it from the video lectures or you can ask one of the volunteer directors during a meeting with them. (And from what I understand the people who volunteer to put on the retreats are average Joes who have real jobs in the real world, something cults generally don't allow.)
From what I understand there's a belief in the (Buddhist?) meditation community that meditation should be taught for free. Of course here in the West it's being monetized and you can pay thousands of dollars to attend a tony retreat in a lush environment taught by people who count Oprah as a personal friend. Then there is the Transcendental Meditation (TM) crowd which have been charging to teach their version of mantra meditation for decades now. (If any meditation sect comes close to being a cult it's TM. Supposedly they have gotten better in recent years but they have a very wacky and dubious history.)
So basically the Goenka folks believe that (Vipassana) meditation instruction should be available to everyone for free. It's a core tenet of their beliefs hence the fact that the retreats aren't glamorous or spa-like. They're for people serious about learning to meditate with no frills or BS.
Personally I think 10 days is a long haul and I'm not sure how I would do should I attempt it. Some people drop out because they can't take the schedule of sitting and meditating for such a long period of time. And many of the people who make it through to the end state that it was one of the hardest things they've ever done. But it's also one of the best things they've ever done. It's definitely a marathon-like experience that will show you what you're made of.
*BTW, some famous celebrities into Transcendental Mediation are Jerry Seinfeld, Ellen Degeneres and David Lynch. (Lynch is a HUGE advocate of TM and has been for years. He is also very weird and bizarre and overrated as a film maker.) Ellen doesn't talk much about it but Seinfeld has done a fair amount of interviews about his daily TM practice. He seems like a pretty good guy and I'm sure that meditation "works" for him. But what is often missing in the interviews he gives is the fact that getting instruction in TM costs money, like $1500 - $3000 to start. That's a lot of money for the average person to cough up. And "advancing" in TM instruction can cost thousands more over the years. When you're a rich celebrity you can easily afford it but when you're an average Jane it's much, much harder. To me that's a dubious practice but to each his own.