There was always an unspoken limit where they cut you off, most said it was between 1-2Gb. This just makes it official. Honestly, with T-Mo officially doing $70 unlimited everything (and includes roaming which an MVNO won't), I can't see saving $20 to be worth it to have MUCH worse coverage, at least in my area.
A specified cap vs. an arbitrary unknown cut off is at least better. $50 bucks (45 with auto renew) for unlimited talk and text with 1.5GB of data to do with as you please (they are apparently removing restrictions about streaming and tethering) on any compatible device you want to use is a good deal, imo.
I currently pay $150 + taxes and fees to Verizon for 2 smartphones and 4GB of data between them (so 2GB each). Compare that to $85 for 2 smartphones with 1.5GB of data each on AT&T (via NET10) network with no contracts and I can use any device with no carrier meddling or bloatware. Seems like a good deal to me, and exactly what I"m going to do when my contract is up with Verizon.
Sorry, I wrote my original post while I was running out the door, let me clarify one thing: If it was between unlimited T-MO (20mb/s down but no roaming) on Net-10 for $50 vs Unlimited T-MO (from T-Mo) that included roaming for $70, I'd rather pay the extra $20. Plus I need to get confirmation from T-Mo that they still have corporate discounts, as I'd save another $11 off the $70 price. Then when you figure 2 lines of unlimited talk/text ($80) plus unlimited data ($40), minus 15% = $102 makes even more sense. As of 3 years ago, T-Mo was unusable for me, but now with their 1900Mhz coverage, it should be a LOT better.
However, I agree... a set limit vs an arbitrary amount is better 9 times out of 10, including this one.