A lot of the points, I agree with. In some cases though, it's fair to single T-Mobile out, and in others, it's not fair to single T-Mobile out.
For example, T-Mobile boasts No Contract as one of their main selling points. But what happens if you cancel phone service? The final bill becomes due, including the cost of your device. To market it as something without a contract, when in theory, it is one is already shady enough. The way I believe it should be is the device stays being financed through T-Mobile, even if you cancel service. That way T-Mobile still gets their money, and the term 'No service contract' still is valid.
As for coverage maps. I think T-Mobile's is hella exaggerated, but all of the carriers do this, to an extent. But to be fair, the author of the article also put that in there.
Same with the shady 3 months of unlimited LTE data. It uses people's data stash first. No where, except in the fine print does it mention that. Even the banners do not have an asterisk.