There are now only hours to go before the most anticipated IPO of the year, if not the decade, finally begins trading on the Nasdaq Stock Market, and right down to the wire, the battle is raging over the company’s valuation and outlook.

On the plus side, Facebook’s underwriters are confident enough about he success of the transaction to forge ahead and raise the target range for the IPO to between $35 and $38 a share from a range of $28 to $35 a share. That could give Facebook a valuation of as much as $100 billion. Meanwhile, brokers are complaining on Twitter that their clients are clamoring for shares in the world’s largest and best-known social networking company, if only because they have internalized the mantra of “buy what you know”. The buzz factor has gotten to work, as well, with the market buzzing in disbelief when Facebook founder and CEO Mark Zuckerberg opted to wear a hoodie rather than business attire to a roadshow meeting.

But there are some more serious questions than Zuckerberg’s sartorial choices that linger on the Facebook horizon. As the IPO date came closer, more potential investors began muttering uneasily about the fact that the company’s rate of growth, by various metrics, is slowing slightly. Yesterday, at D-Day minus two, came news that General Motors won’t be paying to place any more ads on the site, due to the low response they have had to the ones they have already paid for. That simply seemed to confirm the results of a poll conducted by CNBC and the Associated Press, which revealed that 57% of users say they never click on display ads while another 26% confessed they do so only rarely.

So, is the company worth $100 billion? Probably not, concludes a new e-book from Reuters Breakingviews. Indeed, even at $75 billion, the valuation is a stretch, it concludes in the first chapter-like segment, basing its conclusions on some assumptions contained in its analysis. If you want to tweak those assumptions, or figure out what kinds of performance metrics Facebook would need to have to win that lofty a value, feel free to play around with the interactive calculator, below, that is part of the e-book.

That doesn’t mean that Facebook’s IPO won’t be priced at a level that gives it a premium valuation of $100 million or so, however. Indeed, even before the IPO is priced, privately-owned shares were changing hands for a priced that implied a valuation in that neighborhood, as this Breakingviews story discussed. Scarcity value may well cause the stock to “pop” in its first day of trading on Friday, as those investors who feel annoyed that they weren’t allocated all the shares they wanted in the IPO fight to buy more from the lucky winners, who in turn likely will hold on to drive the price higher still.

The real test will come in the weeks that follow, as the initial euphoria fades and the company approaches the day when analysts release their first reports and it must announce its first earnings as a publicly traded company. The higher the expectations that are built into the share price at those critical junctures, the greater the risk factor.

Social networking companies may create a lot of excitement among users, but they haven’t yet managed to generate much in the way of wealth for those investors who have bought their shares during or in the wake of their IPOs. As the chart below shows, of the five major social networking companies that have gone public since early 2011, only one – LinkedIn – now trades above its IPO price.

It’s easy for a company to relinquish its status as a market darling once the charms of novelty wear off. True, shares of Groupon did jump this week when the “daily deals” company announced it had posted a profit and several analysts raised their ratings on the company, but it’s still trading at levels that leave its IPO investors awash in red ink. (The shares were priced at $20 in the IPO; they currently change hands for about $12.)

All in all, the analysts at Breakingviews recommend in their e-book that while Wall Street and rival businesses (think Zynga) may have willingly tied their fate to the success of the Facebook IPO, it might be wise for investors to hit the “like” button, and avoid the “love at all costs and all prices” one.