I don't have any inherent problem with remakes and I'm not opposed to a remake of this movie per se. However, the way the original ends, it actually cries out for a sequel. I would much rather see the next movie...the one where the aliens come back and say, "Hey Earth, remember when we told you to shape or we were going to destroy you? Well, you didn't shape up."
It also looks like they're jumping on the "go green" bandwagon with this. Not that being environmentally conscious is bad, but if that's what every movie with a message is going to be about now, it's going to get a little old. The original themes of getting along as an entire species are still relevant and always will be.
And I'm not sure about the Keanu Reeves casting. The original Klaatu had some charisma. Keanu...not so much.