Sorry, wasn't clear there: EPUB3 as a standard is theoretically OK, but real-world support of it on ebook readers just isn't there yet. And the update cycle is

Sorry, wasn't clear there: EPUB3 as a standard is theoretically OK, but real-world support of it on ebook readers just isn't there yet. And the update cycle is a lot slower than browsers or even mobile phones. Also, do you know what is a great platform for "javascript and interactive stuff"? The web browser!