The first three episodes are indeed on On Demand, but I've only seen the first so far. The characters are mostly kind of bland. Obviously the family is supposed to be the star and I don't like any of them at all. I also agree about the date rape plot-- it's forced melodrama and it was obvious even in the first episode that the friend is the real rapist.
My favorite characters were the elderly couple and one of them is dead already. The twitchy soldier and the druggie chick with the cash cache were also kind of interesting, but I don't think any of them can carry the weight as main characters (unless perhaps the soldier regains his memory to find out that he was an integral part of the Arrowhead Project). Everybody else was pretty generic so far.
I'm not sure from the first episode if the monsters in this are mutated animals instead of creatures from another dimension, but that would be unfortunate. The crazy monsters, including those dinosaur-sized creatures, were part of the appeal of the original story.
I'm not sure where this will go as a series, but I don't think it will work as a humans-are-the-real-monsters schtick like Walking Dead. I hope they figure out that the source of the problem is the Arrowhead Project and a bunch of them band together to make their way there.