As Facebook millionaires party, what future for new shareholders?

An expected 'pop' in share prices never came as Facebook went public this week. But Facebook's IPO was a measured affair, lacking in irrational exuberance, and laying the groundwork for the network's main challenge: Turning 'friends' into consumers.

Speculators hoping for a big “buy, sell” cash out from the Facebook IPO were mostly disappointed Friday as Wall Street agreed that the $38 per share asking price set by the social network’s founder, Mark Zuckerberg, was just about right for the launch of the 8-year-old company’s publicly-owned entity.

The historic IPO – the second largest ever, behind VISA – made billionaires and millionaires out of hundreds of Facebookers as the company raised $16 billion by selling 421 million shares, setting the stage for the evolution of a firm that started as a digital college kid hangout to become a profitable purveyor of personal status updates and “likes” connecting about 15 percent of the world’s population

But as its value rose to rival corporate behemoths like McDonald’s and Amazon, the Facebook IPO also represented an uneasy ascendancy of a company that many people say teeters on being a fad, run by a 28-year-old wunderkind who prefers hoodies and sneakers over suits and ties.

RECOMMENDED: Facebook IPO: Five things to know before buying the stock

Although several underwriting banks had to buy shares in order to keep the price from dipping below its offering price, some analysts saw the measured debut as a good sign, setting the company up for a decent shot at building a profitable ad model to boost the company’s earnings and value.

“Zuckerberg priced the shares correct,” writes columnist Nathan Vardi, at Forbes. “This was not a modest debut; it was a home run.”

The stock price rose slightly on Friday as prospectors prodded before falling back to around $38.

The IPO created instant wealth for hundreds of private share holders, mostly around California’s Menlo Park. Zuckerberg himself is now worth $19 billion, about five times the company’s annual revenues, and U2 singer Bono, an early investor, saw his worth rise by $1.5 billion, making him the wealthiest musician in the world, richer than Paul McCartney.

But the IPO also came amid growing questions, including from General Motors, about whether Facebook’s ad model actually works. GM decided to pull a $10 million ad buy. And with revenue growth slowing, Facebook has also struggled in the mobile space, which will become, according to Zuckerberg, its prime goal this year.

The company has also struggled with privacy concerns, since it uses personal information to target ads. While some polls have suggested that Americans may be tiring of the “social utility,” it has, some experts note, become almost too ubiquitous to fail.

With public investors eyeing the company’s every move, the push to monetize content on the site is likely to be stepped up as Facebook now has to prove it can make money, all of which will continue to test the creativity of the young – and now very rich – Facebook brain trust.

“There is more pressure to make money and I think users see that,” says Roger Cheng, the executive editor of the tech site CNET, in a recent CNBC interview. “That said, people are stuck with Facebook, all their friends are on it. So … even if people are turned off by the ads, it is tough to see people leaving the Facebook service."

That fact alone won’t likely be enough to allay worries among Facebook’s new share owners and the bankers who bought shares to prop up the price.

As the IPO party continues on the West Coast – where Porsches are flying off dealers’ lots into the garages of newly-minted overnight millionaires – “anxiety increases on the East [Coast] – at least for the bankers fearful of Monday morning,” writes tech columnist Paul Sloan.

So far, most Wall Street analysts are holding back assessments until Monday's opening bell. Some, however, are already saying "sell."

“While we like the company, we’re troubled by investors’ perception of the risks,” said Brian Wieser, an analyst for Pivotal Research Group, in a meeting with reporters. “It’s priced for perfection and that’s clearly implausible.”

RECOMMENDED: Facebook IPO: Five things to know before buying the stock