The adapter adds about 3 inches to the rear of the Wii console, so keep that in mind if space might be an issue. The attachment not only converts video and audio into one signal over HDMI, but it also offers a separate analog audio out via an adjacent 1/8-inch headphone jack. We found this especially useful with receivers that don't necessarily allow for simultaneous audio and video over HDMI.
In terms of performance, we couldn't detect any noticeable difference in picture quality using a component connection as a means of comparison. Because the Wii console is only capable of outputting 480p, the adapter is not upscaling the image, but rather converting it to an HDMI signal. That said, if you're currently using the composite cables that come bundled along with the Wii, an upgrade to this adapter or component cables would net you an obvious increase in overall image and video quality.
Overall, this product simply provides a means of convenience. Those wishing for a better picture should not expect the Wii2HDMI to provide one. However, if you're more interested in the luxury and simplicity that having another HDMI device provides, the $40 Wii2HDMI is the way to go.