I heard about this a couple months ago at a conference on rapid prototyping, and I've been waiting for it to come out in the hopes that we would finally have a rapid prototyping solution for user interface designs. I'm basically looking for a balsamiq with lots of built-in animations and UI interaction patterns.
Unfortunately, it looks like this product is geared more towards being a full-featured WYSIWYG for webpages rather than a prototyping tool for UI.
I need something that will allow me to say "when the user clicks on this, this other element slides down"... Preferably without having to do the HTML and JavaScript myself. I don't need it to be production worthy, as my developers will insist on doing the code themselves anyway.
It looks to me like this is a great tool for either people who don't know HTML/CSS or firms that need to kick out webpages quickly where the designers don't want to hand code the HTML/CSS.
Not saying that isn't a huge market, it's just not targeted toward UI prototyping.
That said, if the goal here is to provide a Dreamweaver 2.0 that spits out much better quality code, then this option looks really solid and slick.