Pros
The work is atypical and interesting, and the pay and benefits are generous. The staff is intelligent and the work environment is different than at corporate firms. I'd estimate that 2/3rd of the projects make headlines, which says a lot. The company is both dynamic and has a very good reputation locally. It is a gem on one's resume. The firm is very open in the sense that all compensation guidelines and company goals are discussed openly. You must be a self-starter, and independent.
Cons
Half of the senior staff are overworked a few exhibit poor leadership (though half are inspirational). Some employees are pigeon-holed into a long-lasting project or a class of projects, and are not given the hands-on experience that other staff routinely receive. These aren't the majority of employees, but I've seen it happen a few times. Some associates in the firm were overworked, and wished they could step back down the ladder to an Engineering position for compensation. To make bottom-line profits, the firm outsources some challenging work to proven ex-employees, rather than giving it to eager younger engineers.