Pros
Fantastic opportunities - you are limited only by your own talent, ambition, creativity and drive. Resource - BT has access to world-class expertise in every imaginable technical and commercial discipline. If you can harness this, you can achieve incredible feats.
Kontras
Relatively political environment - it employs more people than many countries have in their adult population; and those countries have coups, civil wars, political and religious factions and wildly diverse views of what is 'fact'; BT has all these same problems, which are a function of large groups of people and nothing to do with specific employers. Slow decision-making - an excessive interest in securing consensus, combined with risk aversion, can make forward momentum very hard to achieve. That said, with enough will-power, absolutely anything can be achieved.