Pros
International experience, introduction to cutting edge technologies + superior training, decent salary (even for beginners and home country employees), well developed reporting and promotion management systems, diversified promotion and career path opportunities, i.e. field engineer easily may be promoted (or transferred) to position HR or research & development segment, operational manager can move to sales or marketing domain etc.
Cons
Whole company built on overuse of human resources i.e. you may forget about any work/life "balance" :12 hrs working day is a norm. For field engineers (majority of new hires among post graduates) average years spent in field before getting promoted to line management position is 6-6.5 vs. 3-5 stated by recruiters on job interviews. Political decisions overwhelms common sense quite often, too much corporate propaganda. Although, working in SLB is a fair proportion of pains and gains.