Pros
You'll work with a young and fun team (other than the management layer) and you'll get a lot of good exposure to search engine marketing that you'd probably not get at bigger agencies.
Cons
Management: decision-making skills are poor at best and promotions are sketchy as they are not based on performance, but rather on whether you are liked by management. They also cannot be trusted as they tend to say one thing and do another. Compensation: very low compared to industry standards. HR: no HR team, so there is no way for employees to address issues. Benefits: limited amount of vacation time, sick days count against vacation time, no flexibility around working from home, horrible benefits for extended family members, no 401k, employee expenses can take months to be reimbursed Team: while the team is young and fun, they are also very inexperienced. All the experienced team members have left due to bad management.