Pros
Employees are given a pretty good amount of responsibility. I was an intern doing strategy reports for clients. There were some really smart and good people working there that I learned from, all of which were gone by the time I left after 9 months. You will get experience you might not get elsewhere - interns are not getting coffee, you are doing actual work.
Cons
Amazed at how many good, intelligent, highly productive people left the company while I was there. Turnover is high at all agencies but Trinet's model appears to be hire and pay low wages as a way to maintain their level of profitability. Because they choose to operate this way (which they have every right to), turnover is even higher here than at other agencies. I fundamentally disagree with this model and I think they really fail to understand the cost to their profitability with a continual revolving door of employees. This affects the quality of work they clients get and the amount of time they spend recruiting and training new employees is brutal to the bottom line. No company is perfect, but I think Trinet squanders opportunities as good, young talent is initially drawn to their company mission and client-types only to be disappointed at what they find when they get on the inside.