[idoh]

I work at a place that runs an ad network for facebook apps (so it is ads in Facebook, but not run by Facebook). It definitely works well in some particular areas, like in driving app installs or reengagement. For example, if you've got an app that has a high ARPU but low virality, then fb ads might be an attractive arbitrage opportunity.

Generally, I think the ads are good if you aren't seeking a commercial exchange right away, but rather are trying to build some type of relationship that can be capitalized later on.