According to the docs, it has local fault injection (I.e. you can tell it to respond with “resources unavailable / exhausted”) which makes it “even better than the real thing” for development. (But have never used it so cannot comment about how well that works).

I usually prefer to develop against as-live-setup-as-makes-sense, because test environments often miss something critical; however, it is often hard to verify (on both test and live systems) error condition behaviour - to debug response to S3 errors or resource exhaustion, you actually need them to happen.

Looks like this project does provide for testing these conditions. Neat.