We think it's fine with our Android Galaxy S phone. BTW, US C turned down the IPhone last year...Said that it didn't make $ sense for them.
You aren't going to hear a lot about them, since the majority of people in the country can't subscribe to them. US Cellular is very good in almost all of the markets that they serve, but they just don't cover that many people overall.
That's why you hear about AT&T and Verizon the most, followed by Sprint and T-Mobile. These are the carriers that are available to the majority of the population.
By the way, I have nothing against US Cellular and would like to see them expand.