Pros
Good Job Security - Good place to build experience. Great first job, with lots of benefits. I work in support, and Cisco has a good system to ensure that I do not bring my work home. Also, for the support field, I am surprised how well Cisco Support Engineers are paid. Salary is definite plus. Additionally, pursing a Cisco Certification within Cisco is easy and inexpensive. There are many experts on hand to help the learning process.
Cons
Bureaucracy. Stifling young talent. Too narrow a scope of expertise, not enough interdisciplinary education or work. I wish sometimes Cisco Management will quick recognize who is a top performer and the motivated and talented folks are. Then promote them or encourage them to keep their development. Currently we only do performance reviews once every year and it seems the distribution of incentives is poor.