Pros
Speaking only for Qualcomm Innovation Center, Qualcomm's Android arm: The company atmosphere is encouraging and helpful, allowing relative freedom for individuals to pursue opportunities of their choice. Teams are small and tight knit and most work is done in labs to facilitate collaboration. There is little bureaucracy to get in the way of work. People are generally in a good mood and happy to accomplish things.
Cons
Having not quite shed its roots as a manufacturing company, Qualcomm suffers from a lack of documentation and testing practices. However this is improving (slowly). Managers sometimes do not have time for their employees due to overtaxed schedules, and occasionally long hours will be required due to tight release schedules and continuous patching of poorly designed software.