Pros
For FTE: People are interesting, benefits are good, work can be interesting. If you land in the right group life can be good. This can a good place for fresh grads to learn to work in a corporate setting although my advice would be a smaller company. Do not stay more than 3 years to prevent the culture from corrupting you. For Contract: The cons I list below are actually pros if you are a vendor/contractor. The culture is so dysfunctional that good people who get work done have a nice potentially lucrative niche outside the corporate hierarchy. Keep in mind that there are plenty of terrible contract jobs too, but you can quickly bug out if they don't work for you. I would rate T-mobile 4 stars for contractors/Vendors and 2 stars for FTE work averaging out to 3 stars.
Cons
Very dysfunctional, overly political and backstabbing IT environment. IT culture is designed to trap, belittle, and make you feel insecure. You are expected to be on call all the time, and managers can do call at all times for insignificant reasons. Wasteful war rooms are happening all the time due to management incompetence. T-mobile has designed a culture of overlapping responsibilities where you are constantly kept in check. As a consequence it is hard to get things done because of the constant approval needed. Groups are constantly bickering, protecting their turf, and trying to sabotage each other. Most managers have been there for a long time, and there is an unwritten rule that gives preference to length of employment. New management with fresh ideas is not trusted and expected to learn the T-mobile ways. There is a lot of turnover in management as the new hires tend to leave. Managers are also constantly trying to steal and take credit for other people's work. Pay is deliberately mediocre and they do not like to pay for talent. HR is the worst I have seen at any major company. Career advancement for ICs (Individual contributors) is limited, and T-mobile makes ICs take a demotion to go into management (the only advancement path). Vendors have free reign over the place and FTE people are shunted aside. The vendors have little skill, little understanding of the business, and little interest in the success of T-mobile. Vendors play upon management incompetence, and build armies of incompetent people. Whifs or corruption are everywhere. T-mobile is the only place I've ever worked where the business people outclass the technical folk.
