I was impressed with its 3-D work when seeing it in the theater, especially particles in the air. Without humans on-screen (for perspective, I guess) the CG stuff was underwhelming, in my opinion.
This had been on my to-see list for some time, but WOW that was so well-made. The recollections of the men are haunting, and I really wonder if humanity has even learned any lesson one hundred years on.