Hi glomph. We tried to design that page to show that the free version is remarkably different than the Pro version. Currently, the free version has no file storage -- it's also missing many of the features on the Pro version's list. Let me know if this is confusing.
It certainly is confusing. Saying the paid plan has 'unlimited storage' and not mentioning storage on the free plan strongly implies that the free plan has some storage.
Further how can you claim to be more convenient than dropbox, when for the majority of users (I am pretty sure the majority of dropbox users have free accounts) setting up a payment system just to share say one file represents a massive complication over the alternative.