This is where careers go to die.
Pros
The best reason to work at T-Mobile is if you need a job to get you by while you are looking for a better one. Everything about T-Mobile is pretty average, really. The pay is not terrible, but it's not great. The benefits are decent. They will talk about “growth” opportunities, but that is more of something that you will have to do on your own, and is not really supported by the company. I don't think they are worse than average, but they talk a bigger game than they deliver.
Cons
T-Mobile is a big company that is still dealing with the effects of merging Sprint. This has created a lot of issues. Both legacy T-Mobile and legacy Sprint employees feel like the “other side” has too much influence. In addition, legacy Sprint employees tended to be paid on the low end, because of the financial difficulties Sprint experienced during the final years of its existence. T-Mobile has not attempted to equalize the pay structure in the newly-merged company, and it it is clear that they have no intention of doing so. I believe the T-Mobile executive management saw the merger as an opportunity to acquire Sprint spectrum, Sprint customers, and a certain number of cheaper Sprint employees. I believe it is their plan the use the legacy Sprint employees as leverage against the higher paid T-Mobile employees. Some of the higher paid employees will find themselves “redundant“ in the next couple of years. Of course, they are not advertising this. On the contrary, they are proclaiming a desire to hire more people. While there is some truth to the idea that they, like most companies, are always seeking fresh talent, the truth is that a shake up is coming. There's quite a bit more that needs to be done to fully merge T-Mobile and Sprint.