$15/month gets you unlimited calling, texting and data. However, Sprint admits that video streaming will be limited to DVD quality (480p), music streaming is limited to 500 Kbps, and game streams will be capped at 2 Mbps. You will also be subject to "data deprioritization" during periods where Sprint's cell towers are congested.
To qualify for the offer, you have to switch from another wireless carrier to Sprint (port your number) and bring your compatible smartphone over or buy a new one from Sprint. And for the last sticking point, you will need to setup AutoPay to qualify for the $15 a month pricing, which is per line. So, if you have a family of four, you'd pay a total of $60 per month for unlimited talk/text/data plus any requisite taxes and regulatory fees.
"There is an audience out there waiting for a reason to give Sprint a try," said Sprint SVP Allan Samson in a statement to CNET. "We believe this is a compelling reason."
We should mention that if this offer sounds appealing at all to you, it will become active starting tomorrow, June 8th. However, it won't last very long, as the promotional offer will be available for a period of weeks, rather than months. However, it's likely that once you do sign up, your $15/month plan will last for at least a year before it shoots back up to the standard $60/month rate.
We suggest that you take look at Sprint's coverage map to see if it's worth given the company a try -- at least for a year while you can take advantage of the promotional offer.