Let me tell you, just about everything here is perfect. It's pretty much a panel-by-panel adaptation (though even with 12 half-hour episodes I could notice a few scenes here and there were trimmed for time). However, every single page comes to life thanks to the wonderfully epic musical score and the little touches added in - such as the character's clothes flapping in the wind, their changing expressions, or the camera work that often focuses on all the interesting details we might have missed in the real novel.
But I'll reserve special praise for the narrator. Even though it's a bit jarring at first to have one guy doing ALL the voices (even women's!), you soon realize that it's basically how it would sound if you read it aloud to yourself, for example. You'll quickly notice that every character is done differently (and perfectly!) - Rorschac with his monotone, gravelly voice, God-like Doc Manhattan and even the whiny Night-Owl just sound exactly like I would expect them to.
So definitely give this a try. I would maybe even recommend this to someone who hasn't read the novel before or hates comic books in general, as on the first read-through all the other extra material (journals, articles, etc) that is included in the printed version (and left out here) would probably just fly over most people's heads anyway. And trust me, like the other poster before me said, if the opening shot and monologue don't draw you in, I don't know what will.