The biggest problem facing Sprint Nextel (S), the third-largest U.S. wireless provider: Its customers are leaving in droves. Which is why newish CEO Dan Hesse has spent a lot of time during presentations talking about improving customer service.

He's also been making the rounds media outlets, talking the same game. The latest: A Q&A with Forbes.com, in which the site notes that Sprint "notched a tie for the No. 1 spot" in a recent J.D. Power and Associates study for the Southwest region. But that's just one region. So how's it going for the rest of the country?

Not great. We don't have J.D. Power's data, but according to stats from comScore M:Metrics, Sprint is still the worst of the four nationwide wireless carriers in customer satisfaction -- and hasn't gotten better.

Some 8.5% of Sprint subscribers are "seriously considering switching providers" -- up from 8.0% a year ago, and significantly worse than the 5.5% industry average. Another 3.3% say they've "already decided to switch," worse than the 1.8% industry average.

Of those who might switch, 32% say they're going to Verizon Wireless, which has the best customer satisfaction of the major carriers -- just 3.4% of Verizon (VZ) customers are "seriously considering" dumping them, according to M:Metrics.

That's not to say Hesse's doing a bad job -- Sprint's problems run deep, a year isn't a long time, and he doesn't have some of the benefits his larger rivals have, like AT&T's (T) exclusive deal to sell Apple's (AAPL) iPhone. And while many of Sprint's problems are real, others are just perceived, which are at least as difficult to fix.

Hesse's best hope for the next few months: That his Samsung Instinct can keep a lot of people from buying iPhones this Christmas, that his WiMax JV with Google (GOOG) and the cable industry goes through, and that Sprint-branded Google/Android-powered phones fly off the shelves next year.

See Also:
More Evidence Sprint's iPhone-Clone Samsung Instinct Isn't A Dud
A Sprint Nextel Spinoff Could Be A Motorola Win
Sprint CEO: 'Not Turned The Corner Yet', Revenue Misses, Customers Still Fleeing