Pros
Long history and excellent reputation in the engineering industry, employee-oriented company that is privately owned and doesn't need to answer to shareholders, many people have been here their entire career (many over 30 years) which bodes well for overall employee support for the company, a multitude of engineering and science disciplines to support complex and interesting projects, the company requires professional certifications for experienced professionals which encourages only the best to work here, not complacent and are always looking for new avenues of work, excellent benefits
Cons
The project management hierarchy is convoluted (i.e., project manager doesn't manage the client??), it takes a long time (months) after you start to get ramped up with any type of continuous billable work, main office is located in Boston so you have to get used to commuting, required purchase of company stock (if you are an approved shareholder) can hit you in the wallet