"Matt Reeves has expressed interest in making a sequel, to explore other people who recorded their experiences during the monster's attack. He had added the end scene where in the background something fell in the ocean to specifically hint at a future exploration of the creature's back story."
Now onto the monster. I keep reading that the monster is now being called "Gwaka". Don't really know how to pronounce that or the origins of it, but that's what I keep finding. Here is a gif of the monster some one probably captured with there phone. Click on the image to see the clip.

Over all I do recommend the movie to everyone out there. Just be sure to sit in the back of the theater. With the camera movements being handheld, you could get motion sickness. I've already heard from many people who left the movie within the first 20 minutes because they got sick. Other than that, go see it and enjoy. I'm sure you will leave the theater with more questions than answers. And if that doesn't bother you, I'm sure you will love Cloverfield.