Saw this at a screening on Weds. Here are some thoughts, non to spoilery.
This is NOT a direct sequel to Cloverfield. Think of it as happening in the same universe.
John Goodman KILLS it in this. Man, he just owns every minute he is onscreen. He made me laugh and terrified me within seconds.
Mary Elizabeth Winstead, goodness she is just gorgeous...wait, that's not what this was about! Anyway, she plays her part perfectly as well. You are experiencing the unfolding events through her eyes, and she exemplifies an intelligent heroine. By the end, you are all in with her and her actions.
The small cast really allows all actors to shine and give moments of space for all the emotions they go through despite this taking place in mainly one location.
This is a psychological thriller/suspense film. The tension mounts until the ending. When....
Really did like it. Much like Ex-Machina last year, I walked into this not expecting too much and walked out fully satisfied as the story accomplished what it set out to do. The sliver of genres pushed together to create what the film became was as creative as it was thrilling.