As can be seen, the "raw" image isn't too good, but there is some hope for the cropped versions after alignment. The alignment is still a bit skewed but that probably is due to not holding the adapter and camera parallel in any axis.

With cropping/editing (and a hard-adapter to keep things parallel), it might be useful for vertically oriented aspect ratios or where cropping significantly isn't a problem. Might be good for web images where resolution requirements are fairly relaxed. It's possible that "even then", there may be some residual keystoning to contend with, but it may not be significant enough to be a problem. TBD.

Note that the above images are all substantially reduced in resolution from the original versions (else you'd still be waiting for it to download).