Pros
Diversity is more than a buzz-word and it isn't just a scheme to get low cost workers. Schlumberger actively hires people in 140+ countries and most teams I have worked on employ more than a dozen nationalities. You have ample opportunities for career growth, it is relatively easy to move from one type of role like engineer to a totally different role if you have the talents for it. Management actively encourages even rank-and-file employees to move around and work in different locations throughout their careers, this has been one of the biggest pros for me as every move brings with it new impulses and a chance to reinvent yourself. As the biggest player in a very conservative industry, Schlumberger is surprisingly innovative and willing to take risks.
Cons
I am no fan of the appraisal system. The system goes by the moniker "management by objectives", but in reality every appraisal is one guys subjective opinion of another. Politics also affect the reviews, every manager knows that a bad rating will de-motivate an employee, so many managers tend to serve those strictly to employees in non-critical roles. The cost cutting measures of the last couple of years are out of whack with the financial challenges we are facing. Schlumberger laid off thousands of people, there is a company wide travel ban in place, nobody got a pay rise last year, we are not allowed to replace old computers etc. All this in a year that is on track to be one of the best on record for the company in terms of profits.