I use the HDMI switch to connect a Philips BDP 7300 Blu-ray player and an Asus O'Play Media Player with an HDMI input of my Philips TV 37PF9731.
I did not find fault with the goods in the slightest. The power supply works fine on both the Blu-ray player as well as via the media player. An external power supply is therefore not necessary for me.
In my case, all unused devices are fundamentally disconnected from the mains. When you turn on each selected device, the device switches reliably to the appropriate input.
When testing the automatic switching when both devices are supplied with mains voltage, the switch switched reliably from Bluray player (Port 1) on the media player (Port 2) to, but not when you turn in the reverse order.
Because it does not depend on my automatic switchover, this represents for me is not a problem. In addition, the remote control is working properly.
Since the transmission of HDMI signals to me seems perfect, I can not understand negative reviews of this product.