After sending DxO customer support a sample image file (Nikon NEF), I was informed that the camera-lens combination I used does not have a corresponding DxO module; in other words, the pair is not currently supported.
Fair enough, and perhaps I should have checked that before testing DxO Viewpoint's Lightroom plugin. But the diagnostic error message displayed by ViewPoint was at best uninformative and, more accurately, misleading: "File does not contain any valid EXIF data." There is simply no excuse for an application failing to provide meaningful error strings.
I then tested the product with what I verified in advance was a supported camera-lens combination and it worked. Sort of. It turns out ViewPoint is not designed to read the metadata required to determine what DxO module to apply from the TIFF it receives from the DxO Lightroom plugin. Even when the camera-lens pair is supported, ViewPoint must collect and parse the metadata from the original image file. Which means that for every image, after the ViewPoint plugin has collected the Lightroom TIFF, the user is required to navigate manually back to the original image (it must be the actual file emitted by the camera) in order to apply the DxO module corrections.
It's difficult for me to imagine what the DxO developers were thinking when they designed a product that required this extra step. It certainly couldn't be difficult to code a finite-state machine that would collect the metadata necessary to determine what module to apply from the Lightroom-generated TIFF.
Worse yet, ViewPoint, which isn't supposed to apply any corrections except optical ones, altered the colors in my test image. I ran the same file through DxO Optics Pro and the colors matched those displayed by Lightroom. In other words, ViewPoint, presumably using the same correction module as Optics Pro, creates a color cast that is absent in the Optics Pro product.
At this point, I give up. Somebody please let me know when this product is ready for prime time. ViewPoint has some nice perspective distortion features. They're not as magical as Lightroom's Upright capability, but they're somewhat easier to use than the manual corrections in Lightroom. (Maybe not as powerful, though; I haven't tried to do any extensive testing.)
But this is a product that seems to have been designed by optical engineers for other optical engineers—perhaps color-blind ones—not by engineers for photographers or, as in the case of Lightroom, photographers who are also engineers for other photographers.
I go back to what I said in an earlier post: what I really wish DxO would do is offer its genuinely excellent automated camera-lens correction technology, and only that, as a well-integrated LR plugin.
[Edited to correct a minor typo.]