Vantaggi
The Pittsburgh office (a.k.a GDViz) has a great culture, friendly people, and comfortable work spaces. I've never had any issues with other employees either on or off projects as there is a focus on hiring for both engineering abilities and excellent cultural fit. The work makes an impact in the real world. Most contracts are with government agencies and the software is used in mission critical situations. Work hours are flexible. Projects are fairly free to customize their own agile process, and management is not heavy handed. The organization is relatively flat, with title differences corresponding to role rather than hierarchy.
Svantaggi
As with all contract work, most of the deadlines are firm. Without careful planning some projects end up in a finish line sprint, requiring some extra time from employees.