Pros
I had a horrible experience here, and it wasn't for lack of trying. I actually won their coveted "Wexcellence" award a few times, but a piece of paper with my name on it and a gold medal to wear around my neck doesn't go very far when you have to pay a mortgage.
Cons
WEX grossly underpays their employees. I began with the company as an analyst and had to fight tooth and nail to get $32k per year. In a future position, I brought to the attention of my manager the average pay for my job in South Portland at different companies of similar size, which was about 15k more than what I was making at WEX. The manager finally said "look, Wright Express just isn't going to pay you the market value." I left soon after that. Best decision I ever made and helped me realize my value. Eventually if you work for a company long enough that doesn't pay at market value, or above, you begin to feel like you're not worth market value. Get out before you convince yourself that this is the best it will ever get.