Invasion had a really innovative and unconventional plot considering it's a show about alien invasion as the name suggests. At first I thought it was almost too unconventional since the aliens we're nowhere to be seen and frankly it just reminded me of a casual drama series. However as things started to roll I was hooked with all the subtle developments. It kept being interesting as the reality started slowly to dawn to the characters.
The main characters of the show are basically these two families who are trying to make sense of their lives after the hurricane. The invasion was actually these lights falling the sky during the hurricane, which changed some people in some ways. Doesn't sound like much of a plot but despite this if you're a a science fiction fan I recommend you watch at least the first four episodes and decide for yourself.
I must also say that most of the characters are fairly interesting for example Mariel who was "changed" by the lights in the first episode going through the changes and making sense of who she is right now. Still the best in my opinion is Sheriff Underlay, because it takes a long time to get a sense on which side he's on and what are his motives etc. Genuinely interesting character. I must also say that there are no clear bad or good guys in the show and that keeps things fresh. As to some negative things, the show did go with the "aliens, they look like us!" approach as so many others. I was bit disappointed to this conclusion.
As the show goes on more of the changing cases begin to appear and more characters start to realize what's going on. In generally the things get more interesting towards the end, however I must warn you that if you don't like shows that don't have concrete ending than this is maybe not for you as some of the things are left quite open. The show was obviously sadly cancelled without a warning. You can really see it from the cliffhanger in the last episode that they really expected another season. In short it was a great show and it's a damn shame it got cancelled.