The CGI was just awful, the characters weren't characters that they did anything with that would get you to like them, or feel attached to them. The story was boring, the start was slow paced, and it had many scenes that weren't at all needed, the "horror" aspect of the movie (The part with, you know, birds, like the title) came in very late, and was horribly done. There wasn't anything scary about it, it was laughably bad. There are so many parts that just don't make sense.
On the upside, this movie is just SO BAD that is hilarious to watch. It's so funny to watch it, and also to think about the fact that there was a bunch of people that had to just be like "Yeah this is good, people will like this".