So what are the results? I would give IE9 Beta a 7/10. It is by far better than IE8 or lower. It does have most of the modern web standards, supporting audio and video tags from HTML5. It is much faster than other versions and more slim and compact. For me it scored a 95 / 100 on the Acid3 test. where IE8 only had a 20/100 and Firefox had a 94 / 100, so a bonus there also. Another improvement I've noticed is that the Remember Password doesn’t come up as a popup but instead a hover over the page at the bottom similar to how other browsers do it. Some of the downfalls to it, is, well that it’s Microsoft. Other than that, visually it does not have some of the features we’re used to in other version of IE. There is no status bar, instead when you hover over a link it shows in a little popup in the bottom. To me I find that annoying. I don’t mind losing some of the web viewing space for the status bar.
There are also very limited good or free add-ons for it as there are in Firefox and Chrome. Although a lot of improvements are built in to it, you can’t fully customize it and make it your own as much as I would like. It also does not and as far as I know does not support default re-opening your last session. Although you can still do it via the New Tab page. Also if you still need to view a site in IE8 or 7 it has an engine switching mode in the developer section by pressing F12. Though the developer section doesn’t seem to have changed at all from IE8 and not nearly as functional as Firebug.
So to sum it up, performance wise it seems good, a far improvement from older versions. Functionality and feel of it is lacking and takes some getting used to. So if you’re a dedicated IE user then this will be awesome for you and the greatest thing ever, and for us web developers, we can’t wait for everyone to start using it when it comes out in full release next year. For you firefox and chrome users it’ll still be a useless blue e icon on your pc, but at least it’ll look prettier.