I will try to answer everyone's questions with one sentence(only 20 hours late)
THIS IS AN HDMI CABLE.
It is not a set-top box. It does not stream Netflix on its own. It does not have Android installed. Do not let the appearance fool you. This is a 30-foot wireless HDMI cable. Nothing more, nothing less.
"Why would I want this over a Roku?" because a Roku is not an HDMI cable. You wouldn't buy an iPod if what you needed was an Ethernet cable.
"Can I do XYZ?" Could you do XYZ with a $5 HDMI cable? If yes, then yes. If no, then no.(As mentioned above, this does require a USB port to power the transmitter.)
Personal experience: I have one of these that I bought when they first appeared on Woot, and it gets near-daily use. The prime advantage over an HDMI cable is that the dongle is very small and convenient. You can pass it around computers without worrying about it getting tangled up or knocking over stuff in the way, or you can shove it in your pocket. Why would you shove it in your pocket so that nobody can use it? I don't know, but you can!
Set-up is criminally easy. Plug the included HDMI cable into the box, plug the other end of the included HDMI cable into your TV or other display of choice, plug box into wall. You're done! It took less time to do than to read. Plug the dongle into whatever you want to stream out of, and the device handles the rest.
I personally have not regretted my purchase for one moment... though I do wish I could have gotten today's price instead of the $100 I spent on it.