I've already got a 50GB Box account through a free promo a while ago...but the account has file size limitations unless you pay for an upgrade. I'd assume this deal has the same restrictions. I forget the upload size limit, but it was enough to keep me from actually using them for my personal needs.

I pay $25/year for 25GB of Amazon cloud storage, which includes unlimited music storage and no upload limits. I'm happy with that deal for now.