Is the Rokinon (Samyang) 85mm f/1.4 Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 85mm f/2.8 test image. Observe the contrast and resolution of these results.
Is the Rokinon (Samyang) 85mm f/1.4 Lens set to 85mm f/2.8 sharper than the Nikon 85mm f/1.8G AF-S Nikkor Lens set to 85mm f/4.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.