It seems to be a fantastically expressive instrument, with a huge dynamic range (ok - kinda like the violin) and the tone has a dual quality to it. I love it. And I'm hoping to hear it live when in China.
Take a look at the performance below. I really love the fact that the artists facial expression never changes from its rather stern reserve, but all the emotion comes streaming out through the instrument's tiny sound chamber.
I've just read that this tune is the most famous of all erhu pieces and is called "Er Quan Ying Yue" (1950, Moon Reflected on Second Spring) by A Bing. It really bears listening to a number of times (despite some terrible crackles in the amplification at one point).
I'd love to know who the artist is, if anyone out there can read the blurry hanzi credits at the start. The text in red is definitely the song title, and I guess the two lines under that are the names of the two performers.