I have been having a great experience on my Asus EP121 and the developer preview of Windows 8. Struggled with the Bluetooth driver, but I figured out that I had to set thing to compatibility mode. Here are the rough steps and this should get you through the woods if you are experiencing some of the same issues:
First, get into your file explorer on the program that you are going to run. Click on Application, Troubleshoot Compatibility.
Next, click on Troubleshoot program.
Click on Program worked in earlier versions of Windows.
Click on Windows 7
Click on Start the Program, but do not hit NEXT until the install completes.
Once the installation completes, click on next. Now, this worked for the BLUETOOTH keyboard drivers from the ASUS web site, but I could not get the Warpia USB drivers to work in a similar manner. I hope this helps someone out there, because I struggled with it until I read a post from a fellow Microsoft employee earlier today.
Good luck and have fun!