D’Angelo was at the forefront of what was called the Neo-Soul movement, which was basically inputting the Classic Soul sound into modern R&B and Hip Hop.  D’Angelo was a throwback in many ways as he was a true artist who sang and penned his own material.  The issue here is that in the last fifteen years he has done very much.  With only two albums and a handful of singles he has a lot of work to do in the upcoming years to reestablish his momentum.