The month that I had us cellular, my phone consistently dropped calls and would not receive service in highly populated areas.
When I attempted to port my phone over to Verizon, the phone which I had from us cellular went into a locked status. When I called us cellular, they stated I would have to wait until I received my final bill in the mail and pay it before they would unlock my phone. Being that it was the beginning of my bill cycle, it will be longer than a month from the time that I ported my phone over to Verizon, that I receive my final bill. During this time, my I phone cannot receive or make calls.
I have ported phones over from other carriers in the past and have never had this issue.
I would not recommend using us cellular not only because of the bad cell reception, but also due to their restrictions which seem to penalize the user for switching to a different carrier.