We've learned quite a few things about John Legere from observing his Twitter feed.

T-Mobile's CEO is a fan of The Walking Dead and Better Call Saul. He likes to run in a snow-covered Central Park. His life philosophy is "Get shit done." He absolutely hates AT&T, Verizon and Sprint, and gleefully tweets about their various mishaps. This is the guy who charged that AT&T and Verizon were "raping" customers (he later apologized).

Legere doesn't pull any punches with Sprint, either:

Legere's often profanity-laced musings on social media and an annual advertising budget approaching $1 billion have helped raise T-Mobile's profile. Since taking the reins at the carrier in September 2012, T-Mobile's market share has risen by a few percentage points. In January 2013, T-Mobile's share was 8.4%. In December 2014, it had jumped to 10% and had leapfrogged Sprint at 8.6%, according to comScore.

In another indication of progress, Legere last month surpassed 1 million followers on Twitter, putting him in rare company among tech CEOs. Dick Costolo has about 1.4 million followers — but then again, he is the CEO of Twitter. Others in the 1 million-plus club include Virgin CEO Richard Branson (5 million), Gary Vaynerchuk of Vayner Media (1.2 million), Square CEO Jack Dorsey (2.8 million, but he's a Twitter cofounder) and Elon Musk (1.6 million), among others.

While no one approaches Vaynerchuk's tweet count of 127,000, Legere's 10,000 is higher than most. Judging only by incendiary tweets, Legere is in a class by himself. Last week, Legere took apart a recent study that was critical of his company; research from Root Metrics found that T-Mobile came in dead last among the top four U.S. carriers in mobile network performance in 2014.

Legere used his bully pulpit, a.k.a his Twitter account, to take issue with the study's methodology (it used "old" and "limited" data and put too much emphasis on rural areas). Arguably, by tweeting about the research to his 1 million followers, Legere gave it more attention than it would have gotten otherwise. On the other hand, he also squashed a data point that competitors could use as a cudgel against T-Mobile in the marketplace.

To traditionalists, stomping out public relations fires may seem more like the work of the public relations department than the CEO. Allen Adamson, chairman of North America for branding consultancy Landor Associates, says more CEOs should take cues from Legere, but they're consumed by other things.

"It's partly generational, partly the huge pressure of time demands and partly risk aversion," Adamson says, rattling off reasons why most CEOs keep Twitter at arm's length. "Once you jump into the social media fray you have to be consistent. It's a sprint, not a marathon," Adamson says. No pun intended.

Mashable recently spoke with Legere via email about his social media presence. Below are several excerpts from that conversation, lightly edited for style.

Mashable: What do you think of critics that say you're promoting the John Legere brand more than T-Mobile? Legere: There is really no difference. I am all about T-Mobile. I live this brand. I am T-Mobile and visa versa. That means I say it like it is, and I am not afraid to take a position on things and stand up for what’s right. I don’t worry about listening to critics. I worry about listening to customers. There are too many problems to fix in this industry. How do you find time to do that? It’s a lot of work, and it’s not for the meek. Don’t kid yourself that you can do this for a few minutes a day if you want it to be real. This the most important thing I can do as a CEO –- listen to customers, learn and take action. Whether it’s on Twitter, in call centers or in stores, staying connected to customers is my No. 1 job. CEOs who don’t do it are missing the point. This is a huge competitive advantage. Have you ever regretted things you've tweeted or said online? If you ask again, I will regret my reply. :-) Would anyone who uses social media today really say "no" to that question? Of course I say things every now and again that I wish I hadn’t … but I can’t think of anything specific right now. :) Why don't more CEOs do the same thing? Frankly, a lot of CEOs are just spoiled, and they would never do this. It’s a lot easier to sit in meetings all day than face your customers every day, listen to them and tackle the big issues that are bothering them. If you are going to engage here, you have to be ready to take the feedback seriously and then act. Execs at big companies (like, oh, say AT&T and Verizon) are so used to ignoring their customers they don’t even know how to start listening to them. I prioritize my time differently. Do you think this approach is for all CEOs, or just those of underdog brands like T-Mobile? First, we are not an underdog brand. I think you mean the guys in yellow. Sure, we are punching above our weight against an huge duopoly with AT&T and Verizon, but we have probably the best brand in this category — and our growth proves that.

Second, no, this is not for everyone, but it should be. All CEOs and companies should be this straightforward, honest and transparent with their customers, competition and employees who are interested in what they have to say. They should all take customer feedback this directly and then be ready to act on it. But very few do, so no, I don’t think this approach is for everyone.