Pros
Their benefits package is great, salary is competitive and work atmosphere is very supportive and full of people who you enjoy working with, for the most part. That being said, if you don't have an Ivy League degree you'll find it hard to move up in the company unless you are extremely networked and have good relations with management. There are managers and directors who are fully supportive and try to promote you when they see you are ambitious, but there are other managers who try and prevent that. Overall, I very much enjoyed working at Genentech. I would return but not until I have been successful elsewhere.
Cons
Very windy and cold usually. The company is growing so the culture is starting to change and the growth of the company may be its detriment. Hopefully, with the acquisition by Roche, the culture is not damaged too much.