Pros
SM Energy is a company that has experienced its share of growing pains but is a great place to work. The upper management (CEO, and COO particularly) are great guys who get to know their employees. The people here really make the company. The salary for technical professionals is competitive with other companies and the benefits are in many cases better than other petroleum companies. There is no pressure to outside the standard working hours but often it happens because people enjoy their jobs and the people they work with.
Cons
Office structure can limit working with other groups or people within the company. Additionally there seems to be some resistance to new ideas from different levels of management that can be a bit frustrating at times.