This movie takes place two decades after the original invasion on Independence Day. The threat is the same, and the aliens are back because they weren't able to finish the job they originally came to do. The people of earth have tried to make sure their defenses are better in case the aliens did come back, but the question is if it is enough.
This was a good movie for a really hot summer day, otherwise I wouldn't recommend it. The first movie was entirely better, and this was a shadow of that one. It used several of the same jokes, and it tried too hard to be too much like the first one without all of the charm and humor of the first one. Will Smith was not back in this one, and while some people may applaud that the reason the film gave for him to be out was just so stupid.
Another reason I had a problem with this movie was that the producer, writer, and director, all tried way too hard to pull on the audiences heartstrings with sappy language and scenes meant to be heartbreaking. I honestly thought they over played it in several areas.
There were of course other issues, for example the plot holes were annoying and I wish that they had been filled or addressed better. Unfortunately they were not addressed which caused the movie to be a little disjointed from the original. It was unfortunate and very annoying.
I personally didn't care for this movie. It was fun as an action movie, but it tried too hard to be higher than what it was made to be. It was made to be a silly movie about aliens invading the earth, but it took itself too seriously and went a little too far into being a serious alien movie (with explanations to boot).