Yes, I built a moderately large system on it that used lots of small shared files. The performance was fairly terrible. There's weird little niggles with it--we had random slowdowns, throughput issues, and things just didn't work quite right.

It was an ok solution for what we were doing, but several times I came really close to just dumping it and standing up an NFS server using EBS volumes.

I also used it a couple of times to store webroots and that was a complete disaster with systems that had lots of small files (Drupal I'm looking at you).

Throughput scales with the amount of data in it, it is in the docs. So depending on the application, even if latency is better, the speeds are atrocious at lower volumes of persisted data.