- Callback methods being called multiple times instead of once
- Attempts to use information before it has been retrieved
- Inability to link a specific call to a specific callback
- An easy to read way of writing simple 'pseudo sync' method calls
- The ability to have several calls to the same method in progress at the same time, even llowing a different callback method to be run for each call, and guaranteeing that the user code will run exactly once for each async invocation
- The ability to configure multiple calls to multiple async methods in such a way that as many of them as possible can be in progress at the same time, while guaranteeing that all needed results are available
And the whole library is only a page long - smaller than the demo Silverlight app included in the download!