I make no bones about the fact that I rather strongly disliked the cover of the Fourth Edition Players Handbook, both stylistically and in terms of content. I feel it sends a very strong signal, almost certainly by design, that D&D is no longer a unique Gestalt of pulp fantasy, fairy tales, Hammer horror, and the random detritus of pop culture but instead a copy of copy of those very things. This was inevitable, I suppose, given the way that D&D's remarkable goulash has forever changed the way we view fantasy. I don't think it's an exaggeration to say that, with very few exceptions, every fantasy created since the late 1970s at least has been either an embrace (and extension) of the Gygaxo-Arneson synthesis or a rejection of it. In a certain sense, we are all Gygaxians now, even if some of us hew closer to orthodoxy than others.
It's no surprise then that Wizards of the Coast, now a subsidiary of Hasbro, would need to do something in order to distinguish D&D from its bastard offspring. If every fantasy out there is D&D or a mutant variety thereof, what then is D&D? As a commercial property, D&D is almost certainly underperforming compared to its erstwhile descendants. When World of Warcraft, which employs a fundamentally Gygaxian fantasy set-up, can pull in over $100 million a month from online subscriptions , why can't D&D do the same? I'm not seriously arguing that D&D can be -- or should be -- pulling down those kinds of numbers, but I'm pretty sure someone at Hasbro asked such questions of WotC. When you consider that the brand name "Dungeons & Dragons" has remarkable recognition in the US, the "re-imagining" of D&D we got in 4e begins to make more sense. (Unfortunately, I think it's simultaneously too much of a change to be a good RPG and too little of a change to be a huge mass market success, but that's a topic for another time)
With that as prologue, let me say that I think the cover of the 4e DMG is not a bad one.
I don't love it. I don't think it's incredibly inspired or anywhere near as good as the revised 1e cover, but it's a solid effort and one that I think hits many of the right notes. For one, it's got a dragon on the cover and said dragon is in a cavern. It's not quite a dungeon as such, but it's close enough and I give it points for that. Second, the dragon looks sinister; he's not a nicey-nicey, please-ride-on-my-back-and-fight-evil dragon. He's a dragon. Now, I don't actually care much for the overall appearance of the dragon myself -- he's too dinosaur-like and spiky, when I would have preferred a more serpentine vibe -- but he's at least something I can recognize. He's broadly archetypal and that's good to see.
The dragon is peering into a crystal ball or scrying device, in which he sees the posers on the cover of the 4e PHB. I think this is just keen, as it ties in nicely with the notion of the Dungeon Master as the overseer of his campaign. I also like it because I think dragons, as immensely long-lived beings, ought to be natural schemers and planners and this illustration implies something of the sort. Some will no doubt see in the cover echoes of the cover to the Cook/Marsh Expert Rules, which employed a similar motif. I'm not sure what to think about that assertion. On the one hand, 4e is first "ahistorical" edition of D&D since OD&D itself, so I'm not sure making an artistic allusion to a rulebook published before most of the new game's target audience was born is all that plausible. On the other hand, I've seen repeated (if implausible) claims that 4e is the result of deep research into the history of the game. If true, someone at WotC might have felt this was an "Easter egg" for long-time fans. I remain unmoved myself, but then I take the heretical view that Moldvay/Cook was in fact another step on the road to perdition, so what do I know?
In the end, I'm left with the feeling that this is a decent cover, probably the best we could hope for with the new game. Looking at it, I feel far more interested in playing the game than I do looking at the PHB cover. I also find it more evocative than than the 3e or v.3.5 covers. I realize this might seem like I am damning it with faint praise and perhaps I am, but I don't dislike this cover. It's far and away the best of the three 4e core book covers and it's more appropriate to the DMG than even the 1e DMG's illustration is. That said, I can think of many other illustrations that'd work better for the DMG than this one and many styles I'd find more suited as well. I'd grade it an A in the C+ world of 4e art, but a B- compared to the revised 1e cover or other illustrations I see in my mind's eye.