Though, I think Cisco is a great company, there are some downsides. I think the number #1 downside for me that has been frustrating is expanding my career within the company. I started at Cisco within IT and after my MBA school, I wanted to explore to the Sales Organization and try to work with the account teams. Though I made that transition, it was very very difficult to crack into it. I did it through tireless networking and a ton of referrals. I will always be grateful for my manager in the sales org. to give me a shot. But truthfully, Cisco is a typical large company that does not allow folks to move from one discipline to another. The company would rather have you quit, gain the experience outside, then come back to the company serving the job function you would want. Or during the most recent restructuring (6k people were impacted), the company would rather lay you off, then rehire folks who have that skill/talent. I hate mentioning that because that is classic business-school 101. However, I know that HR is trying to rectify that problem. However, I doubt it will work due to the culture of the company.
Another downside is getting promotions. Though as I mention that it is a great place to start anyone's career (which is very true), the company does not do a great job of giving you promotions to keep you. I've been at Cisco for 5+ years and never had a promotion. Though, I've had several raises, never received a promotion (keep in mind I went from IT to sales which is maybe the reason I did not get a promotion. Starting in a new org. brings you back to square one on the promotion track). It is very difficult and political to receive promotions at Cisco. So something to think about, if you are interviewing for a position within Cisco, try to get the highest possible grade level you can, If you are a mid-level manager. If you are someone straight out of school, then you are at the mercy of the company compensating you cheap compared to its competitors.