[mati]

And what about handling HTTP 500 errors? Although rare, they can still happen. And you cannot make the user's browser retry in such case (as you could do if you were making the request in your app). Amazon's Best Practices document http://aws.amazon.com/articles/1904 clearly states that that's what you should do:

500-series errors indicate that a request didn't succeed, but may be retried. Though infrequent, these errors are to be expected as part of normal interaction with the service and should be explicitly handled with an exponential backoff algorithm (ideally one that utilizes jitter).

However, I still think hosting on S3 is a great option. They are pretty reliable anyway.