You would be surprised by how accommodating and friendly the people here are. Whether the people I've talked to were in my department or not, they have been friendly and helpful. Although it is a corporation, it still carries the core of what makes startups nice to work for - they are willing to listen to your ideas, as seen in one of their "Big 5" mottos: "We will not bureaucracy ruin good ideas".
The strict restriction on how interns cannot work more than 40 hours per week. Many times I had to give up setting up another experiment because of the time restriction.
Advice to Potential Interns
Make sure that you have at least some curiosity about science. Regeneron is a very science-heavy company, with a heavy focus on development, so if you have no interest in Biology or Chemistry whatsoever, then this may not be the place for you.
If you love science, or have at least some interest in it, you will LOVE it here.