Power Button issues resolved!
A BIOS Firmware update has been released to resolve this problem! If you go to the ASUS Downloads page and look for the BIOS update, currently the 10/24/2013 BIOS is the only one listed for a stand alone download. However, if you download and install ASUS Live Update from the same downloads page, it will detect and give you the option to install a BIOS from 12/2/2013. The software calls it BIOS 220.
Once the update is installed the power button works more reliably, but does still need to be held for about 3 seconds. Once you do this the white LED next to the built in webcam will flash once to let you know the tablet is booting up.
ASUS Live Update software can be downloaded here: support.asus.com/Download.aspx?SLanguage=en&m=...