As DWarrior said, outside of major cities there's no 4G, but Sprint unfortunately charges $10/month just for 4G which you must pay if you have a 4G capable phone, even if you can't/don't use 4G. They justify this by saying basically "if you have a nice phone, chances are you'll use more data regardless of 4G coverage".
What I wish is that they would give me a credit on my bill for the talk time I never use. From my actual most recent bill:
I don't talk to shit.