I'm not building a queue, but a lot of things on s3 end up being queue-shaped (more like 'log shaped') because it's very easy to compose many powerful systems out of CAS + "buffer, then push". Basically, you start with "build an immutable log" with those operations and the rest of your system becomes a matter of what you do with that log. A queue needs to support a "pop", but I am supporting other operations. Still, the architecture overlap all begins with CAS + buffer.

That said, I suspect that you can probably beat SQS for a number of use cases, and definitely if you want to hold onto the data long term or search over it then S3 has huge options there.

Performance will be extremely solid unless you need your worst case latency for "push -> pop" to be very tight in your p90.