Unlimited means you can use as much data as you want. There is no where they say that they cannot throttle you. This is basically what is happening. If user A is using a lot of bandwidth and users B, C, and D want to do something, there is less bandwidth for those 3 because A is taking up a lot of it. What Sprints new throttling plan does is throttle user A only during peak times so users such as B, C, and D can also use the network without having horrible speeds. Sprint has promised unlimited data, which means you can use any amount of data without being overcharged. While some real heavy users may notice it, they will only experience throttling during peak hours or when that specific tower is congested.