Pros
It is no secret that the pay is very good right now. Tell them what you want to make and they will give it to you. You can move up relatively fast for a large CRO. Most have rules about how long you need to be in a position before you can be promoted, but they are not nearly as strict at SYNH. It is a large organization so every person there can have a very different experience. I have about 10 colleagues there that I have known for many years and half are very happy there the other half are looking. So it is hard to say what experience you will have. Mine was negative, but yours may not be.
Cons
The PM II role is not very well defined in the organization. It can function as a true project lead with ALL the responsibility or as support staff doing an overwhelming amount of menial tasks. I did not have adequate training. In-part because I was assigned a project right away and was working before I even had the most basic access to systems, but I also think that I would not have felt like the training would have ever been enough because it is all "education" and not "training" which is just a repository of SOPs and an occasional video with a broken link. This works well for some people who are true self-learners, but I learn from speaking to an actual human being which will never happen in this sort of bureaucratic organization. Just consider what type of learner you are because there are a LOT of processes/systems you need to master and you will be on your own to figure them all out. PTO was extremely hard to take. The recommended notice period for PMs is something silly like 9 months (this can be different based on the project). I took a sick day and it was like the sky was falling. Unlimited PTO just means your support staff will be out a lot and you will do their job while they are gone. WLB balance was really bad for me.