Pros
Variety is the spice of life. No boss to speak of, other than the client. Crazy schedule and fast burn projects make things exciting. Salary starts out a bit on the low side for the expectations and workload, but high performance is definitely rewarded, especially when you get to the manager level and above. Once you get to principal you have the golden handcuffs firmly in place. This place is a total meritocracy. Individual performance based on billable hours is measured, quantified and reported on a weekly basis to everyone in the company. Loafers and people who don't come up to speed quickly with the corporate culture don't survive long. You are surrounded by high performing, brilliant colleagues from top universities. Hard to think of a better environment to strut your stuff. If you just graduated with a Ph.D. from a top university and want to know if you've got what it takes to compete against the best, brightest and hardest working Ph.D.s from the other top universities, then Exponent might be the place for you.
Kontras
Work-life balance very difficult (dare I say impossible) to achieve. This is definitely a company for workaholics. Raw performance is measured and rewarded, so if you are someone who thinks they can rest on their laurels and prior success, don't bother. If your spouse doesn't have a career and wants to stay home with the kids, this may be the perfect place for you. Heaven help you if you are a dual income household with two career minded partners. Nearly all of senior management is divorced or is married to a spouse who has no professional career. No formalized training to speak of. This is a sink or swim career path. You either get it or you don't. You must be a self-starter and come up to speed very quickly, otherwise you will be looking for your next job less than a year after your start date.