Greytones work great for superheroes, just look at Green Lantern 8 as an example. This is a cool cover but I don't think the Moldoff (looks like his work) made the most of the process and perhaps that's why they didn't continue. I would love to have seen what Gil Kane would have done.
I agree this is a very cool cover, but could have been better. Someone could have done a more moody cave scene, imo.
Those greytone freaks are nuts..the Bats would have made awesome Washtone images. Recall the cool Batman Gumcard sets from the 60's that were all paintings......