What happened to the show is that the journey to answering those questions was more intriguing than the result, which involved another alien species getting involved and some amazing leaps of logic that betray the relatively grounded nature of the first seasons. Falling Skies is a good watch, but not a great one, with some creative concepts. However, at the end of the day, it is nothing that I haven’t already seen elsewhere; it is sometimes done worse and sometimes done better.
On the whole, the show is, as the kids say, “mid.” You can catch Falling Skies on Max, and what I can say is no matter how it ended, there’s a clear ending, and it’s at least better than the series finale of Lost.