IMHO, the point is not that the site isn't flashy, but that it doesn't explain why would you want off-site and crypted backups in the first time. The site I would expect for a backup tool is one which scares the visitors to the hell, full of well known horror stories, and showing how tarsnap would have avoided them.

For example, Jeff Attwood, a well known and "smart" guy isn't he? Well, he also thought his hosting provider was doing adequate backups...

Astalavista? They had backups, but the cracker logged into the backup servers using the credentials stored in backup scripts and deleted them. Did you know that tarsnap may use a key for writing, another for reading and another for deleting?

It's true that being an UNIX oriented tool makes it a "niche" product since most companies use a combination of UNIX and Windows servers. But there is still a big chance of success among web owners running small to medium webs for a living on cheap VPS or shared hosting accounts on foreign countries. They should get very nervous every time they hear an horror story detailing how some site dissapeared because of a bad backup strategy...