2.5 GB is per line. I moved one line last month to check (from H2O), and it has been working great so far. Will move 2 remaining lines later this month before renewal at H2O. As mentioned, it is on AT&T (actually cricket is now owned by AT&T), and speeds are capped at about 8 Mbps. If you finish up your 2.5GB data, you can still go on internet, just at reduced speeds (unlike H2), where you are out of luck unless you add extra money).
They also have $25 referral bonus (both both persons), and it posts in about 75 days. If anyone is switching to cricket and needs referral, please let me know.
Any questions, I will be happy to answer.