Pretty bad, on the whole. I suppose it's worth first addressing an obvious feature: it's a remake - a remake of a movie (that despite some admitted moments of cheeziness) is a classic. Which already puts the pressure one. And, to not keep you in suspense, I for one don't think it even came close to living up to the standards of the original. Which really wouldn't have been that hard - the production values in the original were a little weak. While this movie had better special effects, and the acting was at least as good as the original (again, not especially difficult to achieve), the script here was a lot worse off.
Not surprisingly, they attempt here to make the movie more relevant to contemporary issues; instead of nuclear technology, the concern here is with the environment. But the original concept was actually more apropros than some might think; while nuclear weapons were the immediate concern, the real issue is with force and violence. And surely that is as relevant (or more) than it was in the 1950s. Furthermore, with the change in theme, the story is complicated in new ways, as the motivation of the aliens changes. While the aliens in the original were (and I believe were intended to be) somewhat morally ambiguous, here there is almost no ambiguity, and the humans end up nearly unequivocally as the "good guys" as they find themselves in a struggle for existence. All while we're supposed to be worried about the environment. Strange and mixed-up.
Thematic trouble is just the start. This is a more action-oriented story than the original, but, as is often the case with such changes, the action, and hence the movie, also make much less sense. There's a lot of pointless and confused running around, mostly. And, as in a bad '80s action movie, the last five minutes make little sense and don't even follow the established rules or any detectable logic.
I think that's enough of that. It's disappointing. An okay budget, plenty of okay to great actors, and in the end you get a movie that's not just worse than a '50s science fiction movie, but considerably so. Perhaps that's symbolic of cinema in our era.