I just saw it tonight.
I could tell it was long, but it didn't get dreary to me because it kept cutting between all six stories, and kept a decent narrative link between them so that much of the time they either played into each other thematically or scene-wise.
There were a few spots that seemed a little out of place (like the gun chase in 1973, or the Mister Hyde vision that keeps appearing to Hanks throughout the section where Hugh Grant plays a cannibal), but even the futurist fights/chase seemed to fit decently.
The acting was pretty decent (although Hanks was a little off on his accent in spots), and the makeup is pretty amazing. Not perfect, there's only so much you can do, but sometimes actors remained pretty unrecognizable in their various roles.
Not just writing but also editing this movie must have been a real bitch, and I think it deserved better on overall scores. It's one of those pieces that either will be meaningful to you and thus moving, or it won't be and thus won't seem to be a big deal. But as someone who has had experiences being marginalized by the system, as well as someone who views humanity as all part of the same cloth and is tremendously bothered by how we draw petty distinctions among each other simply to ostracize, control, exploit, or limit each other, I was very moved by some scenes to the point of shedding tears more than once. (I was most moved by the 2144 sequence in Neo Seoul, and by the gay composer sequence.)
(as comparison, I might be able to say that a movie like Malick's "Tree of Life" was more artistic, but I carried nothing away from it that was useful to me.)
I think the line that I brought out of Cloud Atlas, for me personally, is that maybe we are each only one drop in a huge ocean (so what can we possibly do?), but then again, the ocean is made of a multitude of drops. And Somni-451 was compelled to speak her truth even if it was going to be squelched. When you experience something profound and real, how can you remain silent even if the penalty is death? There are some things that run far deeper than life, and death itself is just a door.
Ben Whishaw was EXCELLENT as Frobisher, btw, and I think he is playing the new Q in "Skyfall," out in ten days.