Good question. There would seem to be a need for someone to do a contrast and compare between FB and Adwords. But, from what I have heard from others, it might not be in FB's best interest right now to provide any more data. Facebook is not Google.
Kelly Gillease, who works for Viator (?), seemed to agree with you in this report Hubspot released today:
Before diving into numbers set the expectation that Facebook ads are a lot more like banner or display campaigns than search engine marketing campaigns; donít set your sights on Facebook ads generating response numbers comparable to a SEM click-through or conversion rate. Facebook click-through rates are generally lower and conversion rates can also be low. Some advertisers are a great fit for Facebook and see wild success, others are disappointed with the results when compared to stronger, more traditional direct marketing channels. Marketers need to immerse themselves in the Facebook environment and test strategies that take advantage of the highly engaging social environment that Facebook seems to create.
...Measuring social media metrics is trickier as the traditional URL or analytics tracking is often not available. Establishing baseline performance upfront can help isolate increase trends for which the Facebook ads are likely responsible.
She goes on about "branding," which is what you hear when the channel is not providing marketers with the right context.
The non-paid part of Facebook is where you want to work, driving traffic to your emails, blogs and your websites. Ads? There are better channels likely, depending on what you're doing. There are a lot of compelling ad networks forming. And Google is a black hole, too; that is to say, you can always do more to improve your targeting.
I say let someone else go first with the ads on Facebook, finding what works and does not.