Pros
Overall good compensation package, salary + benefits + profit share People are terrific, everyone helps everyone and means it. Interesting projects amidst others that pay the bills. While this is a large firm (17,000+ world-wide), it has a small-company feel. Training of 40 hours is allotted to every employee, some mandatory but rest is enriching. Company structure is unique to any I've worked in. Held in trust, not beholden to shareholders. Employee-owned in the sense that everyone has allotted shares by proxy by which profit sharing is distributed. Not stock per se, but the same outcome. a sense of ownership. Employees are called, "members" and everyone is valued. Office vibe is relaxed in general. Different discipline members sit next to each other to promote cross-pollenation of ideas and how each does their thing. If a person joins as an engineer in one segment, (say design) but seeks to focus or refocus on others, such as sustainability, energy, such shifting is encouraged, Members become more versatile and this helps everyone.
Cons
Any cons are common to most firms of any size- balancing work production with the extracurricular activities, enrichment, training and such. (Current industry trends with professional services commoditization is something no service company can well control.) The work-life balance is seriously encouraged but one's sense of responsibility can take over and work hours grow a bit. This is a function of self-management to a point, but if overloaded, you raise your hand. There is a tendency to underestimate hours it takes to do a proper job and this leads to some stress as a project is being completed,, but this is being dealt with.