Perhaps he is saying that the per-gig cost is not clear. It says buy now for $29, but the extra $0.15/GB/month to use S3 is hidden under "Why use S3?" (you might not expect costs to be there)

We both know what S3 is, and know that they charge per gig. But the market of people who want online backups for their macs don't necessarily know this.

true, but this service is also incremental so it'll (in theory) backup more than 750Gb.

Remember after June 30th it's also (750 * 0.15) to upload it.