is around 300-600MB/mo. Add some streaming in, you could get to 1GB.
Good for Sprint. They are selling a product that really isn't utilitarian (people love the word "unlimited" even though they don't need more than 2GB of data from AT&T or Verizon), but that's the free market.
Sprint has far fewer customers than AT&T, and, hence, no congestion. They also have way more spectrum when you include the CLEAR 4G on the 2600mhz band that's taking a good chunk of the network abuse.