Pros
Good pay and free food (to a certain extent). Big recognized brand. Business class travel. Safety is supreme. Lot of focus on this aspect. Flexible working. Work from home to a certain extent. Good work life balance. No one will ever disturb you on weekends or vacations and on working days also you don't have to slog. Unlimited sick leaves. Misused heavily and employees are to be blamed if this is stopped. Independence to try new things and getting recognized for it. Number of years of experience not the only criteria to land in a job group. This is making many employees unhappy, but I believe its a good thing. If you want fancy titles, this company is not for you.
Cons
Most of the IT work is outdated and legacy. May not give a lot of learning in IT space. People are expected to pitch into a lot of different areas which many don't like as they want to stick to their core competency. Lot of resentment by staff outside India due to their job loss. Indian employees have to be always on the toes to prove themselves. Most of the leadership hired from Accentures, Wipros, IBMs. They are hell bent on making Bangalore office another Indian IT services company. Things move very slow which doesn't give the feeling of IT. But then its an Oil & Gas company and IT is just a support function. Vendors are trusted more than employees. They are ripping Shell apart for years. Lot of things being done just to show off. Leadership does not have knowledge to recognize the real value. If someone is looking for long term onsite, this is not the company for you.