I have taken a liking to Falling Skies and have been watching on Blu-Ray DVD, so I'm only through seasons 1 and 2, since season 3 discs may not come along until March. It's not so much the monsters, as it is the cast of characters. As with 'Walking Dead', you have your favorite people and are concerned for their well being.
I must say that I did like a similar show - 'Invasion' - better. It was a 2005 production directed by Shaun Cassidy (yup, the former teenybop singer). The premise was similar: families and a community infested with aliens who subtly infected selected characters and began altering their thought processes and biochemistry. There was less overt warfare than on Falling Skies, which for me was a plus. Sadly, though, Invasion was not picked up for second season.