Pros
Schlumberger provides a huge amount of opportunity and responsibility right from day one. To add to that they spend a lot of time and money training you with skills that are both useful in your current job and that those that will translate very well into future positions. Turnover internally within the company is significant, its unusual for any professional to remain in a job for more then 3-4 years. Opportunities to move up are always around as a result. Not to mention any personality conflicts will be over with sooner rather than later as one of you will move on shortly.
Cons
Schlumberger is a HUGE company and while they make an effort not to be bogged down by red tape, it simply can't be avoided entirely. They'll keep you alive and safe but make you jump through a lot of hoops to get your job done properly. Also being in the R&D side of the company is sometimes frustrating as the view from many sectors is that the Field generates revenue and therefore carries the biggest stick. In competition for resources to get your job done we often lose out to Manufacturing as a result of pressure from the Field operations.