Pros
Schlumberger is one of those companies where everyone in management started at the bottom and worked their way up. You know that your boss went through the same things that you went through when they started out. Schlumberger is also very respected in the oilfield. You do not have to be embarassed when you tell people where you work, you can be proud to say "I work for Schlumberger." It also has a wonderful development program for new employee's. This program promotes team work and mentoring which help to build a stronger working group.
Cons
There are problems with middle management levels, especially at the FSM and District Manager levels. District Managers are allowed to run their offices as if they were God, and are allowed to make their own policies at whim. Schlumberger claim's that they have a no blame culture, but this is not true. Manager's do not want you to report incidents because this will affect their end of the year bounuses. Also not all employee's are treated the same. Employee's in some departments are treated a lot better than other departments. This is true not just at one district, but at most districts.