Pros
A very young and friendly environment. I often saw my co workers outside of work, which meant going to work much more bearable. Beer in the office regularly, and I could work from home almost whenever I wanted, and as long as I got everything done I was able to make my own schedule. It also was a great place to start a career -- the SEO experience I received has come up in almost every job interview I had after, and I feel confident it will continue to help me.
Cons
Much more about quantity than quality in my writing. The more we were expected to write, the more it felt like plagiarism instead of our own ideas, even if it technically wasn't. The pay was not enough to live in Boston, and I felt like if I freelanced I could make much more. Also, beer in the office is fun, but can make non-drinkers feel out of place and excluded.