I have an Asus and I am going to either sell it or give it away.
In the Asus, the UI is cumbersome. Too many clicks to get to the video or audio, even more when you try and access the network. No thumbnail support. Also, when playing the same video file with the asus versus the WDTV, the video is better looking with the WDTV. Asus has a problem with color saturation. Asus does have the option to adjust the brightness and contrast, but was unable to remedy the video issues using this method.
While the Asus does have some features the WDTV HD does not, it is not worth the loss of video quality.