I live just outside Washington, DC and have Sprint. The service is fine for me here. But then last year I took a trip to Florida and couldn't get a signal to save my life.

In other words, Sprint's coverage is great right up to the moment when it's terrible. Which you can live with if you're mostly in a place where it's great, but which makes it hard to recommend to people generally since you have no idea if they happen to spend most of their time in places where it isn't.