I deal with so many functionality points in Oracle Documents Cloud (aka, Oracle Content) that I'm not even sure what functionality has actually shipped and those that are about to be released in a planned update, so I wont comment on what's there or about to get there.
But I can tell you it's a whole lot more than a mere document repository.
While licensing for that (say the iOS client) is yearly (and not lock-in), once you get going with the product line, it's a bit difficult to move this data off to another service because you loose all data integration with other processes (whichever they may be that I'm not comfy discussing right now).
When a large company moves such infrastructure, the biggest cost is data migration (there are some Oracle groups specialized in that).
From my perspective though (the iOS client for Documents Cloud), we work hard on new feature and integration. We deal with 4 different server infrastructures behind the scene to link up your data. And despite the cloud offering, we're still working on On Premise where YOU control storage.
Not going to comment on Amazon's infrastructure but I was not happy to see my Netflix go when S3 had a flat tire. :-)
My opinion is my own. Not talking for Oracle (my employer) nor am I a representative.