Pros
Super friendly atmosphere, with mostly everyone treating even interns as equals, allowing them to participate in brainstorming sessions and client briefs. There is no obvious hierarchy that is present - in fact, some people were so friendly to me and I found out weeks later that they were actually at very high positions in the company. Also, if you've got a good idea, they love to hear it and encourage you to pursue it! Another pro - the office space is lovely and conducive to creativity
Cons
While there's no obvious hierarchy, the environment can get too gossip-y and dramatic at times. Also, there is often a lack of follow-through on many things, which can get stuck, e.g. a website that hasn't been updated in about 2 years, despite many complaints. Additionally, as an intern, you need to constantly ask for work and hope you are taken seriously at times - otherwise you'll end up bored in the corner!