No you can't download it just wait for another beta version. This was the first open release just wait for a while and they are bound to release another one. I think it will come out around early next year or halfway through 2010.
I've been using it since before the publicly released build 7000. It's exponentially better than Vista in every way. I believe that this is what Vista should have been if it wasn't rushed out. From the new taskbar to the power requirements, everything is better.
I have it running on my 1.5Ghz Centrino with 512MB ram and it's smooth as butter. On my 2.4Ghz core duo with 2GB of ram, it's NIIIICE. I've heard you can go as low as XP standards, as long as you have 512MB of ram, so that's like what, a 500Mhz processor. RC1 should be coming out pretty soon (within a couple months), while the final RTM should be by the end of the year. If you skipped/passed up on Vista, get Windows 7.
We had the Beta version on my photography class' computers for a bit, but the scanners weren't compatible so we had to downgrade to Vista Business.
I was extremely impressed, and other than a few errors here and there, (expected for a Beta version of a new OS) everything was great. I can't wait for it's full release. It worked well on both the laptops and desktops in the class.