The original Avtaar (1983) was a classic that starred Kaka, Shabana Azmi and AK Hangal as the alien who's always been old. As you can see, James Cameron has slightly altered the screenplay for a worldwide audience. He doffs his hat to the first film in style.
I thought it was well adapted; Hangal and Golshen Grover are the only actors from the original in the 2009 version. Watch for them as Na'vi elders.