They're decent in terms of image quality, terrible in terms of animation.
Aside from the obvious problem of motion interpolation having problems with acceleration/deceleration, there's a lot of nuance in the original animation that gets lost when you try to interpolate from one sprite to the next.
Even if you can avoid obvious artifacts, no interpolation algorithm can create new information, it can only derive from what's already there and guess at what's missing.
EDIT: If you dig through twitter you'll find some tweets from animators explaining why the results are bad. As mere consumers we might be tempted to dismiss that criticism as snobbery but animating is a craft and the interpolated results are objectively worse than the original.
Aside from the obvious problem of motion interpolation having problems with acceleration/deceleration, there's a lot of nuance in the original animation that gets lost when you try to interpolate from one sprite to the next.
Even if you can avoid obvious artifacts, no interpolation algorithm can create new information, it can only derive from what's already there and guess at what's missing.
EDIT: If you dig through twitter you'll find some tweets from animators explaining why the results are bad. As mere consumers we might be tempted to dismiss that criticism as snobbery but animating is a craft and the interpolated results are objectively worse than the original.