A movie that had much charm and dignity the first time around was the victim of a rather depressing sequel. I like the idea of the modern twist "to save the Earth" from humans, but I don't think the plot updates well from that simpler time.
It does make you wonder if we humans are really that stupid and violent? Unlike Klaatu, I was not convinced that any truly valid argument was presented for our preservation. The most terrifying part of the movie might have been John Cleese in a totally sober moment, like a defense lawyer making our case. Klaatu is told that only on the brink of extinction do we act responsibly. Then he sees that only in witnessing death do we show compassion. This is convincing? This is a passing grade? Obviously he was confused by the human body he was in, thinking with a human brain structured to rationalize any behavior.
But I don't think either Klaatu-- the first or second-- ever showed enough subtlety to undertake such a mission to Earth. Surely they should be intelligent enough to figure out how to do it right. Unless that's the culture-- to do the saucer, or plasma orb test, and see if they attack?
Frankly, they should have done as the dolphin-headed white-haired guys from "This Island Earth" did. Get some Interociters built and have some quiet talks with cabinets across the globe. Exeter would have been a better man for the job.
Some nice cg effects here and there, but the nano-clouds, though done at a higher rez, were still reminiscent of scenes from "The Mummy," or "The Langoliers."
For me, an unavoidable view, but a B-minus effort.