Pros
Some of the best benefits I've seen or heard in my tenure. While salary may be on lower end of the average range, it is easily made up for with a great pension, high 401k match, annual bonus, etc. Sempra provides great stability during times of economic turmoil. There are so many opportunities within the organization to feel like you are making a societal change (green energy development, smart cars, electricity rates, providing natural gas to developing countries, etc). All organizations have their flaws, but overall, Sempra is an amazing place to work.
Cons
Have to be patient to move up the ladder. Most people start their careers at Sempra and stay forever (a tribute to to how great of a place to work it is) so you have to wait your turn. Can be political environment but so is every large energy/utility company. Depending on the department, long hours could be in store but it is cyclical and there are always opportunities to move around.