Pros
I worked for ERM for 4.5 years. I was able to work on a variety of projects and learn a lot about various industries during that time. There were opportunities for travel if wanted, though after a while the extended travel began to wear on my family life. Most of the people in the local office were friendly.
Cons
There is a strong push for 100% billability. Managing Partners have voiced the opinion that individuals that cannot be fully billable should be fired. However, the additional job duties that are not billable functions do not get compensated through overtime pay. You are consistently asked to work 50+ hours/week but paid at a much lower rate than others in the industry for less work. Additionally, they try to lure you in with promises of an amazing bonus system. RUN! They promise that those who do great work will see 5-10% year end bonuses and are eligible for quarterly $2500 bonuses. These don't happen. At most you see 2% annual bonuses and you might (if a partner nominates you) receive a $500 quarterly bonus once. The additional effort put into the work is not equally compensated. Finally, ERM consistently bills out work at rates around 5 to 7 times higher than what the employees are actually paid. The private equity firm and the partners are then seeing the profits that come from this additional cash inflow, not the employees that are working the hours to complete the work.