Actually yeah I do remember now some 16 year olds or whatever complaining in the cinema after cloverfield. I think it was about how it didn't explain anything. Was ages ago, can't really remember. I want to say one said it was shit and another was saying, what was that about, what was the monster.. but yeah memory is unriliable.. although i am postive the "that was shit" was said.
Personally I really enjoyed cloverfield, only annoying thing was, the story arc was a bit contrived. Was just enjoyable fun, something different, something to get your imagination going. I didn't have a problem with the ending. It was an interesting concept done well.
It's odd how people need things to be spelt out for them. I've seen on message boards online about District 9, people who are complaining about plot holes ect, that weren't explained in the film. However they were all things addressed, even if by a line here and there, but you get enough to understand what's going on. You may have to slightly extrapolate, but it's all there that I didn't find any problem understanding it. If people are worried about the technical details of the aliens, then they missed the point of the films.
Do people really need everything explained in detail scrolling crawl and diagrams on screen or whatever people want.