The link was directly to the SP executable, MS hasn't published the page with the release notes, or they pulled it subsequent to my original posting. Earlier adopters do so at their own risk, and most people would be better off waiting for the final release through Windows Update. The advantage of downloading the full executable early is to avoid the server loads later and to have the executable available for installation on multiple computers and not have to download it multiple times through Windows Update.
You need to do the checksum verify of the download. If the checksum doesn't match, it's probably corrupted. The checksum is in the article I linked to in a message above. I have to redownload myself as the checksum failed on my copy. I have often encountered Windows updates that wouldn't finish a logon after the first reboot. A second reboot would then proceed normally. I suspect it's a timing problem in the delayed file replacement method.
This is just another typical MS cockup.