Just want to add on based on my own experience.
EM is a very large company which is doing very well overall. The company is clearly driven by its mission to enhance its shareholder value. It has very good management systems to allow it to operate as a huge coroporation. Employee wise, they will reward people accordingly just to retain them in service, though their repsonse time to adjust based on market conditions can be slow and less flexible. However, if you are just a average performer, I can say the job can be quite secured. High flyers are transferred to different departments frequently, however pay wise may not be as high as compared to other companies in the oil/gas industry. In singapore, many senior management positions are taken up by foreigners from EM other locations. EM is constantly closing its refining business in other parts of the world, however Singapore is definitely its focus in Asia Pacific.
EM offers prestige and experience in management systems which other smaller companies may not have. There are many people left EM after 5-10 years and join other companies in the same industry, eg supporting industries. The new job nature may be different, more towards service, sales and technical, but as long as people can adapt to that change, the rewards and quality of life is usually much better than in EM. So I can say EM should be treated as a good training ground for other companies in the industry. However, I know many people still stay with EM after many years, not becasue it is a good company (EM can treat employees harshly, and the environment can be stressful and working hours can be very long), but most people are resistant to changes.