Pros
Overall, a great place to work and a great place to learn new skills. As an employee, you'll receive exposure to other parts of the business to see, learn, and execute processes and workflows from varying groups inside the Genentech organization. One of the few organizations that stress cross-training and Genentech does a great job of hiring and promoting internally (mostly good choices, rarely bad). If you're open to learning, have an outgoing personality, and are generally likable you'll do pretty well for yourself.
Cons
Folks are resistant to change, There's not a big incentive to understand the "whys" of what you're doing in QC, and the routine work might be boring for some folks. If you're timid, shy, or anxious.. it'll be rough. If you're an independent person who is not used to collaboration, you will have some trouble adjusting. As with most high-salary biopharma positions, be prepared to work off the clock. The biggest con is the acquisition of the Vacaville Genentech site by Lonza. I suspect annual pay/bonuses and other benefits (e.g. sabbaticals) are likely to be reduced or eliminated. That said, it's better than a total shutdown of the Vacaville site and the work experience will look great on any resume.