Pricing changes don't usually happen this fast in the wireless industry. It seems like T-Mobile and Sprint both have multiple contingencies in place to attack one another based on what goes down each day. Following T-Mobile's announcement of the free LTE upgrade for one year, Sprint has revealed a new unlimited data plan that's only $60 per month. There are a few caveats, though.
In order to be eligible for the $60 plan, you need to purchase a new device on Easy Pay (Sprint's no-contract financing arrangement). You can also bring your own device or pay full price up-front. At $60, Sprint's plan is $20 cheaper than T-Mobile's. In fact, it's only $10 more than T-Mobile's basic 1GB LTE plan. You could grab a Nexus 5 for a relative pittance and hop on Sprint's plan as soon as it goes live tomorrow.
Service quality is still important, and Sprint has had issues getting it new LTE network up and running. If you've got good coverage, though, this sounds like a fantastic deal. Seriously, this is a good old fashioned price war, and it wouldn't be happening if the merger had gone through.