Pros
ESI is forthright and thorough in dealing with its employees, subs and customers -- best I've ever seen. Corporate leadership is honest and as transparent as possible. Legacy employees enjoy best in class benefits. Newer hires have a bit more of a benefits buffet to choose from but those choices come with compensation off-sets -- exactly the same as the rest of the industry. Solid support for professional dues/education.
Cons
Solid rumor that the company founders are stepping away. One (of two) already has. I'm personally confident that the course and conduct of the firm will be set before that happens; it remains to be seen whether the succeeding leadership can manage that. Very little room for professional growth in the company. If you're happy in your position on a contract, you're fine. Little room to move if you're not. Firm generates it revenue from supplying subject matter/technical talent to a federal gov. customer, thus compensation is inextricably tied to what that customer will pay. This means that folks in the same 'job band' largely get paid the same. Solid performers are aware that their less productive colleagues make the same salary. Not much incentive to exceed minimum expectations.