For me, the erhu is quitessential chinese instrument. I bought it the second time I went to China... I made the mistake of not buying it the first time! It turned to be very difficult to play, and I tried to find some tutorial online. I found some very good video made by George Gao and I learned to play the song "Lady Meng Jiang". Actually, I don't understand how my parents managed to endure the pain of listening me playing the very first notes on this instrument!
But once you begin to understand how it works, it is really a wonderful instrument!