Pros
The best reason to work at Cisco is purely to get Cisco on your resume. The company still garners respect from the name recognition. It is also a great place to learn how big business works, with lots of management that does very little and if you are the little guy you will get to see what it is like to get dumped on all the time, which will let you develop techniques to deal with stress and overwork. Any job at Cisco will teach you office politics and give you insight into how playing politics can help you get ahead in a big company. These skill are invaluable if you are planning on working at large companies for most of your career.
Cons
You will not be compensated very well, you will not receive very good benefits, you will be forced to dealing with lots of change without any input into the decisions or how they will be implemented. You are forced to deal with LOTS of management, including VPs that don't even have anyone that report to them. Generally you will be at the mercy of the upper management and whatever benefits you have now will be slowly taken away, without you getting a say into how, why or when they will go away.