Good place for a start - Anonymous employee Shell Employee Review

Users say... "Good work life balance and interesting" "very ethic and good benefits" "The pay is good and once you learn how to navigate the system there is room to move." "The culture is great and supportive yet challenges you to continuously expand your professional skills." "great people and multicultural (though the latter is changing through centralisation and offshoring)." 

Users say... "1. Poor management emphasizes in results solely from data analysis rather than quality or focusing in listening to subordinates" "Continuous restructurings every 2 years mean no job security and teams being understaffed (although certain top management remains same for decades)." "bad managers and cumbersome working with HR employees to get forms." "Long hours and stressful occasionally Cyclical commodity boom and bust" "Career Progression is slow and may lag behind peers in the industry"