I don't think you've seen truly great async support, it's virtually indistinguishable from sync code.

Sync:

  let file = File.Open("foo.txt")
  let data = file.Read(8192)
  // Do some compute stuff with data

ASync:

  let! file = File.OpenAsync("foo.txt")
  let! data = file.ReadAsync(8192)  
  // Do some compute stuff with data