If FB were a mature non hyped run of the mill stock making paper goods, I would say Barron's is right that it should trade between $18-$25.
FB however is not a plain old vanilla stock making paper goods or anything else. It is a highly atypical, new model media stock that has just started making money on mobile devices. As we all know, there were basically no mobile device ad revenues up until a few years ago.
Of course you have to note that they were wrong in their prior claims that the stock would drop to $15 so I don't think anyone objective is following their advice anyway. The stock seems to be trading in a channel between $25 to $32. A huge disappointment and another clear indication that there is no ethics or accountability on wall street.
However this blather that the stock is worth $5 is silly and it's not supported by the facts. The stock is highly volatile and subject to media and PR bias and general antipathy. As long as they keep meeting or exceeding mobile ad revenues the stock will trade at 5x BV. All Zuck has to do is announce tomorrow that the have set up an internal group at FB to study an instant hyper or metasearch function and the stock will jump.
The growth potential is there. FB is a media company that makes money thru advertising, just like every other media outlet. They screwed everyone by overpricing the IPO, but that doesn't mean the stock is worth $10. Get real folks.