GTRI is a great place to work if you want to work on defense-related R&D-type work. Since it is mostly defense work, you need to be US citizen, and eligible for a security clearance.
You get the opportunity to branch out, beyond whatever you already know. That makes it different from large contractors, from what I hear.
You have a lot of autonomy, whether that means you will have time to explore subjects and solutions you might not have otherwise, or just slack off, will be up to you. However things tend to get more hectic when it is time to deliver, or demo to a customer, etc.
In exchange for greater opportunity for career growth, and more personal autonomy, expect to get paid less than you probably would in the private sector (GTRI is technically part of the state gov't).
I have worked at GTRI for almost 4 years; the first 9 months as a student and then became a full-time researcher. The work environment is very flexible and GTRI offers very interesting challenges to work on.The best part is the entrepreneurial-like experience. Employers are encouraged to seek out their own, that is most interesting to them. This could be through submitting your own proposal or finding projects already within GTRI to contribute to.
I have worked for Georgia Tech in the Real Estate Development Office and find that during this economic times the ability to complete the real estate projects that I was brought on to do has not materialized. I enjoy the people I work with and feel I have contributed in many ways to the real estate acquisitions and leased property that Georgia Tech has required. But I find that I am looking to return to the fast pace of the corporate world and to face additional challenges and opportunities.