I bought one yesterday, and can confirm that it works. The first thing I did was upgrade the PTV firmware, and also performed a hard reset while messing around with it to be on the safe side.
It does have some issues with discovery, usually solved by disabling then re-enabling WiFi on the SP2.
I had some teething troubles trying to get 1080p out of it, but this turned out to be a HDMI handshake issue, resolved by modifying my home theatre cabling.
I have no issues with my PTV3000 with the latest firmware. Use it at home for movies, and at work for projecting presentations and network visio's. Never have to reset the wifi to get it to work, just tap charms, devices, and select the adapter. Great little product.
There is lag, its better. The use case is for Video Watching and Presentations. I also use it occasionally if I'm delivery Training a Virtually having the Lync Client with content on the Flat Panel TV and using my Surface for notes and IM.