I actually do not like having Dark Ritual in a black deck that contains Nightmares. Leaves the temptation too great (at least for me) to cast a Nightmare before I have enough Swamps in play to be effective. As a critter smaller than 4/4 he stands a good chance of being blown away early. If you feel a little top-heavy, do what I try to do with black. Run 4 Wil-O-Wisps. They are one of the best critters in the game for only one Mana. 0/1, Flying, and regenerating. Also, if you are worried about type 2 format, they are still printed in ninth, (and should be fairly easy to get a hold of).
As for the artwork, I have 2 Unlimited Nightmares, 2 Revised, and 1 7th ed. I honestly think that the older artwork (with a few exceptions like reverse polarity) is a lot better, and more suited to the card and its effect.
You will NEVER convince me that the new clone, and all the "newer" counterspells, have better pictures. Sorry, the peace sign with the flows of negation magic from them is just the best! (counterspell). And the Clone's old artwork is also great.
As well as one last thing about the art......my favorite artist is no longer employed by wizards, so nothing new can ever equal the old! (Quinton Hoover)