For a US citizen the challenges are many. Too many mid t0 senior level positions are filled by foreign expats (that are cheaper, and they do understand the most complex and advanced market in the world), which makes promotion difficult for US citizens. Senior leaders bring in their own people. Also the US system relies on MBAs, which makes it difficult for US citizens to work abroad in this global corporation. The starting pay scale for a US MBA Associate is more than a Director makes in many other markets. Nowhere else wants to pay for "an expensive American", making the wonderful opportunity for a global career limiting for a US citizen.
Also- work/life balance is a struggle. The company is competitive and forces bell curve calibration for bonus and merit increase annually. Between this and heavy work loads make the work/life balance tough if you want to succeed.