It has a sustainable pricing model with no gimmicks:
- .005 cents/GB/month for storage
- free inbound data transfer
- .02 cents/GB for outbound data transfer
- first 10GB is free with no time limit
- first GB of outbound data transfer each day is free
- for $99 they will Fedex a flash drive up to 110GB from a B2 snapshot
- for $189 they will Fedex a USB drive up to 3.5TB from a B2 snapshot
- there are no "delete penalty" gimmicks that make cost optimization impossible on objects with indeterminate lifespans
For backups, it's hard to beat B2 IMO.