Many advertisers are unsure of how to use Facebook. You still do not have a huge success story that compelling points out “We did it on Facebook” Still too much of a work in progress.
Management is openly commenting that they may not be able to increase the concentration of ads. This physical limitation will ultimately limit revenues.
Laws and regulation relating to privacy and jealousy of regulators may inhibit growth as Facebook becomes bogged down in the tar baby of bureaucracy and politics.
George Gutowski writes from a caveat emptor perspective.