In short, fun but not 100% up to the job IMHO. The stuff that is enjoyable (the 'toy' look) is a bit gimmicky and the stuff it should be great at (edge to edge sharpness) is not its strongest suit. Very very sharp on centre, even wide open but especially stopped down a touch. Unshifted, the best compromise between edge sharpness and loss of resolution to diffraction is at F8. Shifting is harder to analyse and I need to take a lot more shots but so far, if I wanted to get the whole frame sharp, I wouldn't use this lens unless I was feeling slightly forgiving.
Usability in terms of iterating swings or tilts on the D800E and getting the focus right is pretty good if not exactly a doodle. I have many shots where I have almost nailed a complex choice of focus points but not totally got it. No doubt more practice will improve things.
Not sure if I'm going to keep it: once the novelty has worn off, it doesn't really fill its brief perfectly, but I'm not sure what other choice there currently are that would do better. At least rise seems to work well if you stop down a bit and lose the last bits of the sides... but the inconvenience of not being able to select the directions of shifts and tilts and swings is irritating too.
anyhoo, some shots, just to prove I actually used it
A couple of novelty shots...
A couple of swings to get the plane of focus where I want it:
those last two are available here if anyone wants to see what is and isn't in focus...