Pros
Good opportunity for someone who is proactive and will work hard to advance; incredibly laid-back environment; easy place to fly "under the radar" if you just want a job to pay the bills; looks good on your resume; very strong opportunity for entry-level college grads in terms of the experience you'll gain and what you will be able to say you did when you apply for other jobs. This is a good place to work if you're right out of college and looking for a job and there is truly nothing else that works out for you. If you are ambitious and a go-getter who is not afraid to ask for what you want and share your ideas, you can go very far here. However, you also have to have a tremendous amount of patience for unprofessional leadership and a complete lack of support, beginning with your first day when you are handed an assignment for your first report and virtually zero instruction on how to tackle it. After a while, you will realize that yes, everyone there is making it up as they go along - many of the reports published by Hanover are simply the products of a lot of 22-year olds compiling information that they Googled all day. And for many members, it's a good deal to pay the relatively low membership fee to have access to a whole floor full of bright 22-year-olds who know their way around a Google search, rather than conducting their own such research in-house. Members at Hanover are happy; former employees of Hanover go far. It's not a terrible place to put in a year or so of work because it does look great on your resume, but you need to be prepared to make your own way and be able to deal with a frustrating, tedious, unsupportive, and cohesion-less day-to-day work environment.
Cons
Leadership is nonexistent; the company is poorly run; there is zero transparency about any important decisions being made; some departments (marketing) and individuals (certain high-selling marketers) are favored; a incredibly unprofessional CEO who leads through intimidation. The negatives about Hanover lie in its leadership. The director of the research department should be replaced. There is no transparency about any company decisions. Additionally, as an employee there I had reason to believe that the marketing team falsely advertised the research team's services: I once sat in a meeting in which a marketer spoke to us about how our research capabilities are described to prospective members, and told us that he markets the team as containing individuals with MBAs and PhD's. A researcher raised their hand to ask whether, indeed, there are MBAs and PhD's on the research team - there aren't, of course; just a bunch of 22-year-olds and Google. The research they produce is fine and works well for the members, but the company's services should not be falsely advertised just so that the marketers can make a buck. (Furthermore, the marketing team is higher paid - with many more opportunities to earn bonuses - than the researchers who are actually producing the product being sold. This is a large part of the perception, accurate in my opinion, that marketers are favored at this company.)