Genmaicha is another one of those teas that you have to brew properly to get the full experience of its wonderful-ness. It needs a lot of patience and TLC.
They key here is really to read the brewing instructions. It says to steep in 87C water. So that’s not the temperature of the water that comes out of your kettle. Let the water cool for 4 or 5 minutes, then steep the tea for another 4-5 minutes only. If you don’t do this, the tea will become astringent and gross (I know this from personal experience).
The brown rice gives it a nice toasted flavor that goes great with the green tea :) It is really popular in Japan and you can find it pretty much any sushi restaurant. I’d really recommend it!