Actually he was on Stephen Colbert.
Rightrightright.
Saw it the other day with my wife - like others, I think it is well worth seeing for the amazing artwork in 3-D. Some of the images could easily have been cartoons by Leonardo da Vinci - particularly the series of horse heads. Just brilliant work by some ancient artist of talent.
I was somewhat dissapointed that the actual narration was so thin and woo-ish, but then, so little is actually known for sure. The reptiles thing at the end had us both laughing. 
What really startled me was that the images spanned some 5,000 years, yet were so stylistically similar. Also, in 5,000 years, you’d expect a lot more of them, if making the images was some sort of ritual thing.
The thing that strikes me about the cave art is that there’s no way renderings that beautiful sprung fully-formed from the head of the artist. He had to have practiced somewhere. But where? On wood? On rock? Stick drawings in the dirt?
Makes me wonder what other beautiful art he (they, I guess) may have produced in less enduring media, which didn’t survive the passage of time.
As for the movie, well, it started dragging for me. The material was stretched too thin.
I’m wondering if the peoples who made the art lived in skin tents like the native american tepee. The native americans often used the skins as canvass for their artwork, so perhaps did the hunter-gatherers who made these cave paintings (though oddly, the native american artwork appears much more stylized).
I can well understand the skepticism of those who first found this stuff - it is just too technically accomplished, one would think, for “primitive” art. Obviously, one would think wrongly …
One thing I’d have liked to have known is more about how the artwork was made.
I agree that when viewed as a movie, it was too long - but, perhaps selfishly, I didn’t mind having more time to view the art. I could look at that stuff for hours. 
That sounds like a reasonable possibility.
So I saw this movie with my friend Jim a couple of months ago. We are both huge Herzog fans from way back. After the movie, I told Jim that the crocodiles were just Herzog being his crazy old self, but Jim said it must be more than that. We did agree that it was the height of hilarity and couldn’t stop laughing at his final narration in the theater.
About an hour later, he had figured it out:
Throughout the movie, Herzog mentioned that the cave paintings were like a movie. The painters made paintings of animals that we no longer see in Europe and which did not live in caves at the time, but their images have lasted for tens of thousands of years. Herzog is making his own painting (the movie itself), and he has inserted into that same cave (in the sense that the scene is jarringly inserted into a movie about the cave) animals which do not belong there. This is what he means when he says that the crocodiles may someday make it to the cave. He is trying to relate to the original painters as artists.
I’m almost speechless (who, me?) that anyone can say not to see this movie in 3-D. It’s like a gigantic 90-minute advertisement for why 3-D is wonderful and why it will eventually take over the world, once the bugs are ironed out. Pay no attention to the naysayers. If you can see the movie in 3-D run to do so. And I mean run, because it sure won’t last very long at a movie theater. Remember, the drawings themselves take advantage of the dimensionality of the cave walls. They require true 3-D to appreciate them as they were created. The 3-D effect is essential, as well as wonderful.
Leave as soon as the crocodile sequence comes on. Really. It will hurt your brain.