Black Ops looks awful on PC, the textures are low res and the colors are all a murky gray-ish color. Hideous. I own Modern Warfare 2 on both PC and XBox and the PC version sported phenomenally upscaled textures and overall had a great look. Vibrant colors...etc. Black Ops is just disgusting from a visual perspective, it definitely looks more like Modern Warfare 1 moreso than MW2.
But from a gameplay perspective, Black Ops is the best Call of Duty in a long, long time. Certainly better than any of the Modern Warfares. There are actual real counters now to the overpowered perks. Someone's laming with explosives/noobtubes, you equip Flak Jacket. Someone's abusing claymores, you equip Hacker. They took Stopping Power/Juggernaught out of the game which means you can actually use the other perks instead of always going with one of those two.
Overall, great gameplay when compared to the last four CoD's (CoD2 was the last good one, and CoD1 was by far my fav).
As an aside, I had to disable VSYNC in order to avoid getting headaches with this game. Strange, vsync works great in MW2 and MW1... but in Black Ops there's just something not quite right...