Your first impression might be that this is just a blurry photo, but the obverse of this specimen is very mushy and deeply dished as well. Note the lack of any rim. The reverse is absolutely unremarkable, a completely normal strike on that side.
Seems as if there's a solid consensus on the nature of this error. If I understand the matter correctly, in most instances the press would continue to operate and many such could be struck before the material capping the die wears through or falls away. So as far as errors go, then, these shouldn't be too rare, the valuation being somewhat subject to whether it's an early or late stage example. For this particular specimen, I've no frame of reference to determine where on that scale it might be.