Pros
If you do your work and make a general effort to get along well with others, you will do extremely well here. The job and objectives of the department are straightforward, not a lot of the politics that you tend to see at other agencies. Get to see a lot of different client verticals and websites, great for learning and improving your skill set. People internally are always willing & able to help. Clients are usually "real" people and not giant corporations where you are talking to 10 stakeholders and everything is a mess. Clients are generally reasonable and don't get to bully you. The company does a good job of handling divas internally. The people who tend to flare out here are usually those who think they are the best at SEO ever and just don't listen to anyone. If you like to think critically and are always willing to experiment and bounce ideas off of others this is a great place to work.
Cons
If you are looking for a freelance type of arrangement where you just do whatever you want and don't have to answer to anyone, this is not the place for you. Some people come from a freelancing background and have a hard time adjusting to working at an agency.