It's highly impressive, but the question has to be asked: is a web browser really the best interface for a system like this?

The fact is that audio latency, hardware support and plugin support (amongst many other factors) are always likely to be severely limited when running in a browser environment of any kind, let alone on top of the Flash run-time.

This is a great toy, and huge respects to the creator, but if you're even remotely serious about making music, you'll be ditching this within minutes and picking up a custom-built music environment which goes nowhere near a web browser at all.

Sorry, but anybody implying that this is a good reason to retain Flash is going to have to come up with a much more convincing argument.