Pros
The people at ArenaNet have a dedication and drive that is very hard to match in the industry. They seek out the top talent and setup a culture to share knowledge and grow the people around them. I have worked with some of the most intelligent and caring people at ArenaNet. Everyone took pride in their work and had no problems helping each other out or staying late to finish their work. A lot of the people at the company have loyalty for those around them. People stay at ArenaNet out a sense of loyalty to the game they helped make and a belief in the product. I have worked at big company's like Nintendo, and Microsoft and I can honestly say ArenaNet was one of the first places I felt welcome at. Designers, Programmers, Artists, and QA were all friendly and more than willing to sit down and meet the new guy. There were groups that always got to together for lunches and held nightly gaming sessions. People were always willing to include you into their evening or weekend plans. I have made some good friends at ArenaNet I will hold onto for a long time.
Cons
ArenaNet has become a toxic environment where people are worked to their breaking points and then told to keep working. The number one problem that seems to be plaguing ArenaNet is burn out and fatigue. People are often asked to work 10 to 12 hours a day and often to come in over the weekends. Another factor leading to the constant burn out and fatigue is re-scoping of the releases. Teams will work for weeks and months on content for releases only to have everything change a month before the content is launched. This requires the teams to redo a majority of the work for the release while still trying to meet the original deadline. ArenaNet has also become a political cesspool. People are being locked into positions not because of a lack of skill or talent, but because they don't suck up to the right people. I have seen employee's with glowing recommendations from their teams get passed over for employee's who can barely do their job because of who they were friends with at the company. The people who actually do the work are too valuable to let them advance, but then the incompetent people make all the business decisions. Management is often ready to scapegoat their people as well. They make all the decisions, but take none of the blame when things go wrong. I also wanted to talk about is the talent. Like I mentioned above, the talent at ArenaNet is great and there are a ton of dedicated people. The downside of all of this is: The good people are leaving the company. The politics and overworked environment have caused quite a few people to leave. Almost everyone who helped make Guild Wars and helped launch Guild Wars 2 are gone. You now have a company that trusts analytics and data over people's intuition or that listened to their community. People feel like their complaints are not being heard and many feel frustrated in their lot at the company. Also be prepared to make way less money that almost any other studio in the area. This company was competitive for the games industry about a decade ago. Unless you are an Artist or a Programmer expect to be paid about 30% less than any other studio in the area.