Facebook app ia really very annoying. As this app runs in the background everytime you put the net on it gives you a popping notification alert with an annoying sound which sometimes you are not interested to read.
Friend suggestions, profile update, add cover images, birthday notifications these things are quite painful for those who does not want to update much.
And the final and the main drawback is the size of the app. Everything it updates it get bigger and consumes more data and space. Having more than 100 MB app in your mobile makes your mobile slower in functionality with annoying notifications alerts.