Sprint has announced a temporary sale on its unlimited talk, text and data plan. For the next four days, new subscribers can get the plan for $50, down from the $60 it is normally. It’s specifically designed to take on Verizon’s $50 5GB plan, and on the face of it, that seems like a good deal.

But of course, a few caveats apply. Unlimited data is certainly better than 5GB of data, but Sprint’s plan, just like everyone else, isn’t actually unlimited. Mobile video and music streams are capped at standard definition, your mobile hotspot or VPN data caps out at 5GB per month, and if you exceed 23GB of mobile data a month you’ll get throttled.

Then, there’s the matter of Sprint’s network. Although it’s been improving for the last decade, it still comes in last place in the biggest crowd-sourced network survey, with coverage and download speeds consistently lower than the competition. (Other studies, which rely on “road-testing” a number of specific locations, have Sprint closer to the rest of the pack.)

Still, if Sprint’s availability is good wherever you need it, and you’re not a particularly demanding mobile data user, this is a great deal for a single line of unlimited data. The promotional pricing lasts until March next year, which should be enough to work out if you like Sprint or not. And, if you port a phone number over from another network, you can also use a Sprint promotion that’ll give you a $200 prepaid credit card for your troubles.

Chris Mills has loved tinkering with technology ever since he worked out how to defeat the parental controls on his parents' internet. He's blogged his way through Apple events and SpaceX launches ever since, and still keeps a bizarre fondness for the Palm Pre.