I was on this service for some time as a tester. Because I'm a dabbling minimalist and frugal enthusiast, I got my cellular data down below 250MB per month. As far as I can tell, there isn't a plan out there that can beat $22.50 per month.
Imo the big downfall is the requirement to use a Nexus 6. It's not a bad phone, but it also isn't terribly good. I recently went back to iPhone and joined another slightly higher but still low-cost carrier.