Pros
RDI places a lot of value on hiring high-quality people which means if you like working with other smart, professional and skilled people, you will like your coworkers. They also place a lot of value on keeping employees happy. You have some say in what projects and clients you work on and they will try to accommodate your requests for certain types of project and technologies (within reason). Although there are a few workaholics, most people work 40 hours/week and there is a lot of flexibility to set your own hours, work from home, etc. They have a generous leave without pay policy (assuming you can afford to take leave without pay...)
Kontras
The casual, laid-back approach at RDI can be a bit jarring if you are coming from a larger, faster-paced company. I eventually got used to it and now I like it. But it's not for everyone. Pay, vacation, insurance and other benefits are competitive with other small consulting firms, but seem inadequate when compared to larger companies or government jobs. There has been a push to improve benefits in the last few years. Hopefully this will continue to improve. The quality of project managers varies widely. There is very little attempt at mentoring. Most employees are expected to be self-directed and ask for help if they need it. This can be intimidating if you are very junior. If you start as a junior employee, your experience could vary widely depending on which team/project you join.