A modernized, darker interface (adjustable in brightness) was introduced to help designers focus on their artwork.
Effects like drop shadows and glows were optimized to render significantly faster than in previous versions. System Requirements for v16.0.0 Adobe Illustrator CS6 16.0.0 -32-64 Bit- Updated Patch
For the first time, users could apply gradients along the length, across the width, or within a stroke itself. across the width