Pros
Excellent training. Very good R&D providing some of the best tools in the industry. If you are willing to sacrifice you can advance quickly in the company. You will "see the world" whether you want to or not, haha. Money in the oilfield is better than most industries. Salaries at Schlum are comparable to its competitors.
Cons
Forget about a home life. The company strives to take over every aspect of your life- before long you will only know people who work for big blue. If you start to get comfortable in a location (ie. settling down), expect to be immediately uprooted and moved to the other side of the world. Management rotates constantly in each location. Part of this seems to be so that management and field personnel don't become too attached to each other- makes it easier to downsize when business slows.