Pros
You know the phrase "If you're the smartest person in the room, you're in the wrong room"? Medidata is the right room. The amount of amalgamated experience in the company is staggering. I joined a sales team as a software sales guy with a few years of experience, and my direct peers have decades of clinical trial experience. There's a lot to learn, but the team is amazingly helpful, and the resources combined have been great, from in person sessions, to recorded learning, to documents & information that are easy to find and understand, I was terrified to start, and four months in, I'm still just scratching the surface. If you are looking for a challenging place to work - and one who compensates you VERY fairly for that work, this is the place to be.
Cons
If you want routine work, a lax schedule, or dislike change - this isn't the place for you. Additionally, you really need to be self motivated - everyone is more than willing to help if you ask, but you have to ask, because everyone is busy completing their own challenges.