From Gokul's interview with AdExchanger:

1. Data. Facebook isn't doing anything with it. When asked if Facebook ever planned to switch on its data for ad targeting, Rajaram said only: "Not at this time."

2. Facebook Pages. "Organically, you get anywhere from 15 percent to 20 percent of your fans, that you reach organically. In order to reach the remaining 80 to 85 percent, sponsoring posts is important."

3. Mobile. Rajaram says Facebook will NOT introduce banner ads, leaving it dependent on Sponsored Stories—which aren't as obvious or intrusive as display advertising. He says, "we don’t introduce content which would not be there otherwise—like a banner ad or something like that—in mobile, it’s a much easier transition for us from a pure product development point of view." That's fine ... except that advertisers LIKE obvious and intrusive media. The mobile screen is comparatively tiny and Facebook has turned its back on a major part of the real estate it offers.

4. Offers. "When we survey users asking, 'What are the reasons you Like a page on Facebook?' one of the primary reasons was people want discounts, coupons, and deals."

5. Speed. Facebook is rolling out new products so fast it's confusing for clients. Here's  how Rajaram says Facebook communicates with its main ad partners, the so-called preferred marketing developers (PMD).

6. Facebook Exchange. Facebook's ad formats are a creative hurdle for some buyers. Facebook's ads come in different shapes and sizes than standard web format banner ads—which means that clients have to create separate campaigns just for Facebook, before they buy on Facebook.

7. Video. Facebook is one of the largest servers of video in the world, and video advertising is a lot more lucrative than display advertising. Yet, they're ignoring this opportunity.