For what it's worth, the strongest thing about Falling Skies is its premise. The aliens have arrived, attacked, and the world is in shambles. Unlike recent alien invasion dramas, V and The Event, there is no turning back. The characters are in a shit hole and don't have numerous tools are their disposal to bypass plot holes. Compared to the languorous plots of the recent alien invasions, Falling Skies is already on great footing.
That said, a lot of the first two episodes doesn't land. Between the action and discussion of the dire situation--which is very good--is a melodrama, one which lacks any draw. Tom and his son Hal try to get through their problems while taking care of Matt and looking for Ben, Tom's third son who is missing. Meanwhile, Tom is getting closer to the doctor Anne. None of this is particularly inventive or emotional, what with the flat acting. Worst of all is Hal's personal problems, juggling Karen and the obvious attempts by Lourdes to woo him. None of this would be too much of a problem if it were only a small part of the show--except it isn't. These parts of the show take up lots of time and divert attention from the fighting alien parts.
The writers preemptive deny any criticism of the Mech's design by having a character ask why they have two legs while the Skitters have six. I have a bunch of ideas, but it's impossible to narrow anything down without further knowledge of the Skitters. Hopefully the writers have a better idea than I do.