Thanks, Serge for pointing this out. There’s something wonky with the URL you provided. It produces an error, page not found.
Well, it’s a good thing some folks haven’t rushed to install Service Pack 1 since SharePoint Design Manager is providing enough fun and games with its corrupted packages messing things up.
It’s a good lesson to test things in a development or lab environment first.
According to Joerg Sinemus blog article: http://blogs.msdn.com/b/joerg_sinemus/archive/2014/02/26/sharepoint-2013-service-pack-1.aspx
We have recently uncovered an issue with this Service Pack 1 package that may prevent customers who have Service Pack 1 from deploying future public or cumulative updates. As a precautionary measure, we have deactivated the download page until a new package is published.
As soon we have more information, we will update you.
Apparently if you used the SharePoint 2013 with SP1 media to install SP2013SP1 you should not have the issue. You will have the problem only if you installed SharePoint 2013 SP1 on an existing SharePoint 2013 installation.
Also see Todd Klindt’s article: http://www.toddklindt.com/blog/Lists/Posts/Post.aspx?ID=486