Mouse over to see the difference in vignetting when fully shifted at f/11 and f/3.5 with no hood but a filter in use.
The above image was made with the Nikon 24mm PC-E - the lens which sees the most use - and is a good example of its merits and drawbacks. It has great acuity and contrast in the center at all apertures (diffraction becomes visible at f/5.6 to f/8 on the D800 though) and improves all the way into the (as seen here) fully shifted corners when stopped down to f/8 - f/11. The rendition of out of focus areas is great too - see this image, taken at f/3.5, or this image, taken at f/11! It exhibits very little (unshifted) to moderate (fully shifted) distortion, no focus shift when stopping down, little flare/ ghosting but suffers from significant field curvature at infinity focus (corners are in focus at a distance closer than infinity). To overcome the latter limitation, stopping down to ~f/11 is often necessary. Vignetting is pleasing at f/3.5 and clears progressively as stopped down, the exeption being the furthest shifted corners, which stay significantly darker, even at f/11 (see the image above for a comparison of a fully shifted image at f/3.5 and f/11, both without hood). Chromatic aberrations are generally under control but significant when shifted, and since the in-camera correction doesn't work when the lens is shifted, you will unfortunately have to resort to the *.nef (raw) image format for later correction (see What about RAW?). The lens is great to focus and a bear to tilt/ shift for its smallish knobs - this can be quite annoying and may even limit its use in cold environments. The flash housing of the D800 can get in one's way as well, although it hasn't yet prevented any desired tilt/ shift or combination thereof that I needed. The alignment of tilt and shift can be easily changed with a screwdriver if desired (warranty would be lost though, I presume). If you don't know what you'd use the tilt/ shift function for, the Nikon 24mm f/1.4 is a much better choice. The following examples are not additionally sharpened.
Image quality center at f/3.5 and f/11 (both jpeg, 100% crop, mouseover): Note diffraction.
Image quality difference jpeg/ raw center at f/11 (same 100% crop, mouseover): Note the typically superior shadow rendition in the D800's raw files.
Image quality corner at f/3.5 and f/11 (both jpeg, 100% crop, mouseover): Note the superior quality, marred by chromatic errors, at f/11.
Image quality difference jpeg/ raw corner at f/11 (same 100% crop, mouseover): Note the lack of chromatic errors in the raw file - the real reason to resort to raw with this lens.
All in all, I'd say this is pretty decent performance. My main complaint is field curvature at infinity focus. Next up is distortion when fully shifted. The rest of the issues mentioned might be annoying, but they can be worked around easily enough.