The site changes its policy a lot, and there have been cosmetic changes to the site that I've heard friends complain about.
I've never had a problem with these things. The apps can be extremely annoying, because there are so many that seem like a complete waste of time. It would be great if there was some sort of filter.
The site is set up with the idea of connecting you to people you already know, and I jokingly refer to it as "the anti-social network". You can only make a small number of friend requests in a day (while facebook will still make friend add suggestions to you).
Possibly the number one worst thing about facebook (and definitely why I dislike it so much) is how disconnected the support team is. There's no HUD that tells you how many friend requests or pokes you can send in a day, but if you go over that number too many times, you could get your profile deleted, and although you can write the support team, the reply will sound like a bot and basically say "sorry, we can't help you".
I've had my profile deleted twice: once for sending too many messages (via facebook mobile), once for an unknown reason, without warning. I know friends who have had the same experience.