I don't feel its the biggest pain to be honest, at least not in the .NET world where the Async API is so persuasive. I don't think the paradigm would suit Java - the API changes to make it ubiquitous would make it take too long to add value. People seem to code with it (the Async workflow) just fine, and it's a decent model to write some async algorithms. For example firing a few in parallel, starting a task but leaving it running and awaiting it later, etc. The advantage for me is that there is some overhead with Async dispatch - the abstraction of coroutines, green threads, etc is cheap but isn't free and maybe seeing where it could prop up isn't always a bad thing. There is value in knowing that an operation could be async, at least in my time programming and it has a cost that you may not want to pay, defer, delegate to someone else, etc especially in hot loops (e.g. IO).
As a single anecdote working in both languages in my current job in a cross platform environment when having to write Java it feels just that bit more painful, and just that bit harder to get the same performance for the class of apps I write. YMMV.
