The mechanics for AdWords are more complex for sure. But the concepts are much simpler.
AdWords: When people search for something, we'll show them your ad, which they'll click, and then buy something.
Facebook: At various times, we'll show people your ad. People will click on it, but the vast, vast majority won't buy. But you've just engaged with them. So you need a fan page and the right kind of content to put on it. If you do this right, you'll build brand loyalty and increase sales in the long run. Did we mention you can use Facebook ads to drive fans to your Facebook page?
Conceptually, Facebook is way more complicated, and less easily outsourced. You can hire an AdWords guy, throw money at him, and get results. With Facebook? Not so much. You can try to outsource it, but it's expensive, and everyone will tell you "you're doing it wrong" (because you are), which is becoming a very common theme with Facebook ads.
If everyone is "doing it wrong", does "it" really work?
When selling AdWords, the most common objection I get is "nobody clicks those links". That is, of course, extremely easy to overcome.
When talking about Facebook, the first question is, "what's a fan page, and where are these ads? Can you just do it all for me?" They usually haven't got a clue where to start, and their first instinct is to pass it off to someone else so they don't have to think about it. There's a market opportunity there, but it looks a lot more like traditional media advertisements (low effectiveness, opaque results) than online ads.