Pros
Great culture - they really invest in you as an engineer. They care about hiring the smartest possible people and then empowering them with the tools and resources to get the job done. Plus there are some world-class engineers there that lead by example and help develop younger engineers. They also care about engineers not burning out - retention rate is high. Plus you get all the cool tech things in SF: great view, great food, flexible hours, etc. Product is very engineering driven. Not afraid to move forward quickly on new, cool ideas. Tons and tons of interesting projects to work on. Easy to switch teams or work on a project for a different team for a short period of time. Lots of room for growth, both in terms of engineering and career wise. More and more opportunities to become a team lead, a "senior" engineer (there are no titles), or to simply learn a lot about a part of the stack you're not used to. Most importantly, great people. Everyone's really bright, and because Meraki cares more about intelligence than background, there are a ton of brilliant people with non-cs backgrounds (bio-engineering, astrophysics, etc). Something about that just makes it more interesting to come into the office every day. Lots of people go out after work to climb, bike, drink, etc.
Cons
I don't interact with Cisco at all, nor does Cisco have an impact on my day to day at all. However, the shift from Meraki to Cisco Meraki can make it harder to attract top new graduates who are hearing about Meraki for the first time. Once they get in the door, they often don't care, but I think we're probably missing some of the top talent because they hear Cisco and don't think it's cool.