I looked at the beta of this but now its for sale (you can download a fully functional trial here) and all I can say is, "this thing totally rocks!".
You get advanced WYSIWYG design support for any kind of ASP.NET or HTML page, CSS taglets that actually show you what the rendering looks like (you can just highlight an element in Design view and right-click on a CSS style and choose "Apply Style"), and (Damn - I don't know how the HELL they do it but...) the ability to import a complete ASP.NET web site -- over HTTP -- and start working on it! It's got features up the GAZOO and it's also very easy to learn to use.
I gotta tell ya, this is the engine that will be built into Visual Studio.NET "v.Next" (Orcas) as the built-in ASP.NET HTML editor designer, and if it's gonna be anything like what you get with Expression Web, you can just take your Dreamweaver 8 and uninstall it, because there isn't much of anything I can think of that you would want to keep it for!
It takes a lot to get me excited about a new piece of software lately, because I've become so jaded from all the hype, but in this case I am happy to make an exception!