With all the noise T-Mobile is making, it’s easy to forget that the other U.S. carriers can do some interesting things as well.

Sprint announced yesterday new service plans that would offer customers unlimited data, texting, and talktime for as long as they keep their accounts active (or as long as Sprint stays in business). The new plans, which start at $80, are available beginning today, and current Sprint customers can sign up without extending their current contracts.

Sprint calls its new effort the “Sprint Unlimited Guarantee“, and it puts the carrier in a very different camp from AT&T and Verizon, which have both snatched unlimited data away from their customers. On Sprint, unlimited is here to stay. (Unsurprisingly, Sprint is charging an extra $10 a month if customers want to run their phones as personal hotspots. Sprint isn’t that crazy.)

While this all sounds pretty solid, the problem is that “unlimited data” isn’t particularly useful if it’s coming over a sluggish network, which Sprint has become increasing known for. Obviously that will change once Sprint completes its¬†Network Vision rollout ¬†later this year — but for now, Sprint is still a bad sell for a lot of people.