Pros
You get to make your own career at TERC. Junior people can join onto an existing project and contribute as a developer or researcher or support staff, and there is room to evolve and grow. Within many of the work groups, there are leaders who are passionate about mentoring and growing new leaders. As you gain expertise you are often encouraged and supported to write proposals for new projects. When those proposals are funded - you are your own boss and can lead the line of work you truly believe in. TERC is an extremely family-friendly and flexible workplace. Many employees are off-site and it is completely equipped and supportive of telecommuting. Benefits are good. There are many different lines of work at TERC and there is always something new to learn from someone.
Cons
TERC is a soft-money organization working in a competitive environment. It takes the cream of the crop to get funded for new lines of work. In the meantime, you work for other people, and sometimes have to work on several different projects to make up a full-time position. Because there are a lot of off-site folks, and because people are often working on different lines of work, there are sometimes lulls in amount of time people get to spend networking and cross-fertilizing (but this is changing I think - there are concerted efforts to make space for more interactions and community among staff).