As far as I know, the only issue is that we don't support Windows atm. Which in most cases is fine -- you can develop on windows using vanilla asyncio, and use uvloop when deploying on *nix.

As a heavy user of asyncio and uvloop, I haven't found any downsides yet (well, other than no windows support if you're on windows). Async Python takes a little learning, but generally speaking I think it's one of the cleanest implementations of async programming to date.