Pros
Madrid is an excelent place to live at, no doubt about that. Nice working environment if you can manage to know the right people and have good relation with them. It is possible to balance family and work time and you don´t have to worry about work after you leave the office in the arternoon or during weekends. Holidays are very well respected too and you can take them when planned. Lots of holidays, 22 days plus one week in Christmass, plus spanish religious and national holidays. There is a nice international environment. ... You will never get fired.
Cons
Working at the Madrid HQ is not a place to learn and become a good exploration geoscientist, everyone is too busy doing his/her own work. -Bureaucracy plays an important role in every desicion and all levels, it is very frustating when things have to be done fast. -There is no sense on how to do things efficiently, mainly because budgets are big and noone really cares. -Salaries are not competitive with other oil and gas companies. -There is a big difference between working in other offices worldwide (Libia, Brazil, etc) and the Madrid HQ. The latter being the not so fullfilling place to work at, because it is away from all the operation sites (away from the action).