It may be that I was unfortunate with the item, but the one I received had HDMI port not working. I've just commenced the return process.
The device is beautifully made and super light. Looks like being of very quality build. The other ports I tested - they worked. I could even plug my docking station USB (with two monitors and mouse connected) into it and the transfer onto my computer was successful. However, I didn't need an extension cable but a fully functional hub so I can have peripherals connected even when I'm travelling.
Overall could be a very good item and based on the reviews it seems it works for the most.