If you can script it with JS, that can be a huge advantage. Lots of interesting compositional ideas become available when you have a Turing-complete scripting interface, ideas that are extremely tedious to execute in a DAW.
Having this all be accessible over the web is another advantage; not having to pay for and/or download a big heavy DAW to develop, collaborate on, or interact with your beats opens up a lot of possibilities.
It will be a long time before something like this can compete with a DAW in terms of polish and breadth of sounds, but it still offers a lot of interesting musical ideas to explore.
Having this all be accessible over the web is another advantage; not having to pay for and/or download a big heavy DAW to develop, collaborate on, or interact with your beats opens up a lot of possibilities.
It will be a long time before something like this can compete with a DAW in terms of polish and breadth of sounds, but it still offers a lot of interesting musical ideas to explore.