Let me just first say that this is a good show. I know I will sound negative, but I actually really enjoyed this show. Also, I need to mention that I have yet to start season 2, but I have finished season 1.
Pros:
1. The premise of the show is really good.
2. I felt like I was still learning about each of the characters until the end. There is a lot of backstory for many of these characters.
Cons:
1. Many of the characters are unlikeable. Some will make absolutely stupid decisions that make no sense. The dad, Jim, might be the most annoying character I have ever seen in any show. While most characters are not annoying, the ones that are will make you start rooting for the monsters more than the characters you are supposed to be rooting for.
2. I felt as if the tone shifts somewhere around the fourth and fifth episodes. In the beginning, it felt much more like a horror show, but then later, it somewhat loses that feeling. While there are certainly parts in the latter half that will scare you, they feel less frequent than in the beginning.
3. Some of the acting in the show can sometimes be pretty bad.
I would give this show about 3.5 stars out of 5. Overall, it is a good show, but there are certain things that will just anger you.
Edit: I just finished season 2, and other than it lacking direction at some points, I liked it more than season 1.