Pros
If you work in one of the core environmental consulting practices then ERM is probably a good company to work for, however if you work in other specialist areas it doesn't come anywhere close to meeting the competition on compensation or reputation. There can be some good opportunities to work on interesting projects. ERM has a flat organisational structure - you have direct contact with senior management and fast response times. Good support services. All IT is in-house. Very responsive and knowledgeable. 5 star service.
Cons
ERM has several consulting levels: Consultant I, Consultant II, Senior Consultant, Principal Consultant, and Partner/Tech. Director. They try to make out that there is no 'gradism' and everyone is a consultant. This is not the case. There is a strong reliance on the established hierarchy of grades. Junior consultants (CI and CII) have limited client contact and often only get involved in delivery and not design of projects. You've got to love your job at ERM because the pay and reward is significantly below market rate. The London office has hot desking. I've seen this work in other companies but ERM has it so wrong. The desk layout is intrusive leading to a awkward work environment. You have to book your desk each week and aren't always able to sit close to your team mates, or even get a desk sometimes.