Personally I loved this movie, it had everything, a city been destroyed, a giant monster, huge weapons, people in danger trying to find their friend and get out of the city. I know a lot of people complained that it was awful because of the way they did the filming, but I thought it made it more intense as it was like you where watching it for real, like it really happened. I nearly jumped a few times as well, I loved the scene where they are running into the underground and they just get inside, so awesome.
I saw it on the first night it opened over here and a few people actually walked out and didn't come back in, no idea why, I wondered if they where feeling sick or just couldn't handle not been able to focus on the screen which did annoy me a little at first.
Only complaint I have is that nothing was resolved in the end, we still have no idea where this thing came from, why it was in the city, why was the place now called Cloverfield, all we know is that it's still alive which is what the voice said at the end of the film.