Edge is currently a free download from the Adobe Labs site (registration required), and is a quick and easy installation.
There's a lot that's familiar in the Edge user interface, and if you've used Flash, you're going to find Edge very easy to use. Like current generations of Flash design tools, there's a visual design stage where you can drop in visual elements. You can choose initial and final placements for elements, and apply transforms that change shapes by rotating, skewing and scaling. You can also apply transition effects, much like PowerPoint. Edge comes with a large library of transitions, which it calls Easings. These can be used to bring images in and out of the animation.
One thing to remember is that Edge isn't Flash. Flash has had more than a decade of development, and can take advantage of its own run time. Instead, Edge is a tool that builds on a set of developing standards and that has to work with browsers that are implementing those standards in different ways and at different rates. You're not going to be able to use Edge to do the same things as Flash for a long time, if ever.
HTML5 designers need tools like Edge to get the most out of the next generation web. There's a lot of promise here, even if this first preview only delivers basic animation features with no interactivity. We're looking forward to further Previews, and to see just what Adobe does to continue simplifying the more complicated parts of HTML5 development.