Pros
Stable company, with close to the best benefits program in the industry. Savings plan has won national awards for its low fees and quality of investments offered. medical benefits are outstanding. The Corporation insures itself, so they are maniacal about safety and health, but their medical plan means you have no worries. The IT Company is the branch that handles geoscience and engineering computing, so it's not accounting or commodity server work that can be easily outsourced.
Cons
ExxonMobil is known to be very procedural, very top-down, and competitive. This is what makes them the biggest and most profitable, however. Employees routinely work together on cross-functional teams, and get along well (I've almost never met an employee I couldn't like and admire), but similar job titles and rungs on the career ladder are force-ranked against each other.