I really, really like this thing. It works with almost everything I tried it on: Linux, Windows, iPhone, Macbook. It's great.
Turns out it's using Bluetooth Classic (this is mentioned on either the website or the docs, but I missed it), so I couldn't use it with a Bluetooth LE-only receiver, which I needed for other purposes.
The docs, at the time I bought this, were only available in Japanese, but thankfully it's fairly easy to figure out how to use just by playing with it. You can also try Google Translate on the website, which worked pretty well.