The main thing I hate about facebook is that the user interface is incredibly bad. For example, things show up on your 'wall' (sort of like an unstructured forum), and you often have no way to see the thread that led up to them being there.

The next thing I hate is that they're a bunch of corporate whores. If you've been following the news, they just recently decided it would be ok to invade your privacy by 'auto-sharing' anything that might be commercially useful, like who among your buds said something about a new movie. Monetization coming soon, folks! You have to figure out it's happening, and then manually opt out.

The third bit of bile is directed at social networks in general: A recent Pew study shows that teens are increasingly unable to navigate face to face interactions. While this is mostly a byproduct of texting, social networks have to share the blame.