Is the Canon TS-E 90mm f/2.8L Tilt-Shift Macro Lens sharp? This page visually answers that question. Shown above are 100% crops from a lab-captured 90mm f/4.0 test image. Observe the contrast and resolution of these results.
Is the Canon TS-E 90mm f/2.8L Tilt-Shift Macro Lens set to 90mm f/4.0 sharper than the Canon TS-E 90mm f/2.8 Tilt-Shift Lens set to 126mm f/4.0? The image quality comparison above also answers that question. Switch between the results to see the sharpness differences between these lenses.