Pros
Zynga was in the right place at the right time to benefit from the explosive growth and viral marketing of Facebook. They had spectacular success up until 2012 despite tedious, uninspired game designs.
Cons
The company exists to enrich the founder and his friends, management cannot be trusted because they are focused on their own needs, not the needs of rank and file employees. The company's rapid success attracted a bunch of phonies and posers who were only there for a quick payday. Massive brain drain due to the stock's collapse has robbed them of most of their talent. The company was built around Facebook gaming, now that mobile has eclipsed Facebook and Flash is pretty much dead, Zynga has been unable to transition to mobile as well as more nimble companies.