While it Leads you to believe it’s about alien invasion, which it technically is the catalysts to the problems people will face, it’s about relationships and love.
It never answers any questions about the aliens, it doesn’t elaborate on the 3 different types of aliens we see, and leaves a lot to be wanted if you are watching this for Aliens.
Now, it is a decent love story of sorts, the relations ships have a decent background and add to the “helpless feeling” that they want you to feel.
Lastly, it’s not the greatest series, lots and lots of holes, but not terrible either. I watched the whole thing with out quit sooo it might be something you enjoy, I hate unanswered questions so I didn’t particularly enjoy it.