Pros
I cannot think of any, maybe they pay salary on time.
Cons
Long hours of work, lots of broken promises from senior management, and plenty of office politics if this is something you enjoy. They also don't take on board real professional advice which results in lots of unnecessary work or just a temporary fix that results in a massive workload to redo things later. Also turnover is very high in some departments. They also don't understand what is meant by quality and insists on strange way of doing things. If you ever worked in any of the reputable big CROs, you will find their quality and standard shocking, to say the least. I am also aware of many customer complaints about quality of work, and many of these are basic errors that should never have occurred in the first place.