This is tough. I love T-mobile. Without a doubt the best customer service and best pricing options of any carrier in North America. You can call this an opinion, but it's not... the numbers support it.
Alas, our hometown hero (T-mobile is N.A. HQ'd in Bellevue, WA.), lost nearly a half-million contract subscribers in Q1:2011. Now, That number is slightly deceiving, as they actually gained a fair number of "pre-paid" customers. But in the end, the net results are nearly 100,000 lost customers in Q1:2011. Detrimental? No. Painful? Yes.
T-mobile says the tough (sequential) quarter is due to the increased competition from the other major carriers -- namely Verizon and Sprint (We remember the Sprint results from this past year were actually on a positive track). But, the reality is that this mainly sounds like fodder for the AT&T acquisition.... which I can't say I approve of, but I've also come to grips with the idea that my vote doesn't make a difference.
As some of you know, I am very passionate about North America's wireless carriers: "passion" is a fluffy word I use in substitute of "strong distaste". Mark my words... Wireless carriers and ISPs will be a stronger force than the Oil producers in 15-years time. That may sound silly, but I can assure you that Data will eventually be a higher valued commodity than Oil-based Energy.
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I work in Tech and Real Estate. I love both of them.