I'm all for the networking program, Facebook. Which was why I joined it not too long ago. I love their unique features vs. Myspace and Yuwie, and they definitely are a great resource for gaining readers for your blogs and so forth.
The one thing I don't like about Facebook, which really isn't a Facebook problem itself... All of the features it does have available that members can add to their page. This is more of a user problem since it is optional to add these features. However, if you happen to find a member's page where you have to scroll down for what seems like several minutes, just to write on their wall (leave a comment), it can get somewhat frustrating.
Here's my advice if you're a Facebook user. KEEP IT SIMPLE. Don't add tons of add ons to your page. It only slows the page down or keeps a visitors scrolling which can result in the last visit they make to your page.