Pros
None, unless you consider incompetent scientific managers who require visa sponsorship or deplorable human resource and legal practices to be positive attributes.
Cons
Beware of Regeneron's legal practices, during on-boarding you are required to sign a non-compete agreement which may prevent you from working elsewhere if you decide to leave. This practice has been outlawed in other states, but NY is slow to catch on. Many of the other reviews warning of a cultish and hostile work culture are true. If you are considering accepting a position be especially wary of groups with foreign monocultures in middle management - there is a severe lack of ethical values and standards associated with these groups. A group of individuals in middle management for the R&D side of the business were exposed defrauding lower level employees within the same focus area of their scientific knowledge and experience. The response from HR, legal and upper management was an attempt to cover things over by coercing employees who were aware of the problem to sign non-derogatory statements. Citizenship status is also used by HR and legal to convince employees towards a given viewpoint when they become embroiled in these situations. Be forewarned if you decide to accept a position at Regeneron, you may be gambling with your career - there are systemic ethical dilemmas lurking just beneath the surface. Presumably one reason the IT department is such a mess is that they have to be involved with problems like this one, where there is a clear electronic paper trail to hide.