I have to say that for free, and for a beta, I think Start8 works fine. Like others, it would be so much better if you come out with a production version, maybe even paid, that actually uses the Win7 interface.
Microsoft claims the interface is now simply an application. If this is true, I'm hoping you are going to come out with some amazing replacements for Metro. While the speed of Metro is great, it is just plain fugly. Please start announcing something soon. The under the cover changes to Windows 8 are actually amazingly good. (Improved NTFS and toolsets, smaller footprint, better support for SSD and hybrid drives etc.) However, it's interface makes it the girl with the "good personality" at the dance. Please do your plastic surgery.