This is a great device for accelerating h.264 encoding on the Mac.
I'm giving it 4-stars instead of 5-stars for one reason only: the quality of the encoded quality is not nearly as good as that provided by Quicktime Pro when transcoding 1080p video. The upside: it's fast. Perhaps this is something Elgato can address in a future software update as the issues involve artifacting during high motion segments and slight softness in general. Perhaps not enough to bother most consumers, but it is readily apparent to anybody that compares the results.
But, when converting standard definition video (such as DVD video_ts) to AppleTV or iPhone/iPod it really impresses with fast and high quality transcodes.
In summary this unit will please consumers wanting to transcode SD video and most HD. Pros or picky consumers will still want to use software methods to transcode 1080p video at the very highest quality.