Update: No longer playable online, but you can download the files and play it locally.
Major plus is that Grant has already included a pretty decent selection of GameBoy Color titles, of which the original Shantae is one. And on top of that, he has also given you the ability to drop your very own .gb or .gbc directly onto the emulator to play them, as well. Needless to say, my productivity level will probably reach an all time low because of this.
So if you don’t mind your productivity level dropping either, I definitely recommend checking it out.