Pros
Ubisoft is the best of the bunch for big publishers in the video game industry as an employee. I appreciate the decentralized decision making (teams have a lot of autonomy), the values which extend all the way to the top of the company at the c-level (trust creative people, and they will do great things for you), and the support. The Singapore studio has exited its "startup" phase and is becoming a more mature studio - but hasn't lost its ambitions. It's still a place where I feel a lot of energy and enthusiasm when I walk through the doors every morning.
Kontras
Every company has niggling issues - and Ubisoft is no exception. One of the big trade-offs is that game companies tend to be "led" by one group or another - design, tech, marketing, or business. At Ubisoft, its business and design. Which means that technology, for example, is viewed as a "solution to specific problems" rather than something that enables new businesses. If that's what you're looking for (hardcore R&D), Ubisoft is no Google.