S3's uptime is probably an order of magnitude better than I can provide myself. From 2010-2011 I worked with a medium-size MogileFS cluster, with about 160 million files and 50 TB of data, triple-replicated. We had great uptime until we ran out of I/O capacity on the metadata DB. Then we had a week of 10% downtime, while we ordered new database servers from Dell.

As far as I remember, S3's US Standard region hasn't had a serious incident since Fall 2012. That's a pretty great uptime record in general, even though it's terribly frustrating on days like today.

My current company spends a few hundred dollars a month on S3. I certainly couldn't match S3's uptime at that budget. Maybe I could do it at 2-3X the budget, but with that budget it might be easier to mirror my files across multiple S3 regions.