Not quite as good of a deal as it seems at first glance, at least for me. I have two lines on Verizon Edge with the 10gb plan, and before taxes and fees I'm paying $210/month (2 iPhones).
I priced out 2 iPhone lines on this Simple Choice T-Mobile deal, and even if I go down to 3gb per line, it still priced out at $174/month after you add on $10 for each line for Jump and the device payments. If I stay at 5gb per line to compare apples to apples it's $194, so only $16 difference.
You might save more adding on more lines, but even with Verizon it's only $15 per extra line on the 10gb or higher plan, plus the device payment, so it's really going to be fairly similar. I guess the savings is if you're willing to go with a lot less data like 1gb per phone.
Edited to add: it looks like maybe the deal in the op isn't on their website yet, and that apparently they're giving 2.5gb/line for the 1gb price, which changes it a bit (assuming I can get it with 2 lines and 4 lines isn't a requirement). I was pricing the 3gb and 5gb plans. So if I was willing to go with half the data I currently have, the bill could be $154 instead of $174, if I'm reading it right. Interesting, but not sure I'll bite. I would have to really watch my data with that.