Just some thoughts...
1) Facebook has close to to 800 million users... currently 1.7-1.8 billion people in the world have access to the internet. I think it's safe to assume that Facebook will never have 100% ... also the rate of increase in people signing up is slowing down from a peak in 2010. Facebook also doesn't have an option to delete an account... meaning people who signed up in 2005 and never use their account anymore count in that 800 million figure.
2) Facebook revenue fell from $1.13 billion (Q4 2011) to $1.06 billion (Q1 2012)... although it was up from Q1 (2011)
3) Their profit (or net income) was $205 million... 12% lower than the first quarter of 2011
4) A $30 share price would value Facebook at $75 billion, yet they have revenue of under $5 billion and profit under $1 billion.
5) Google+ is the first real competitor to Facebook and just released in summer of 2011 (in 9 months they've grown to 100 million users)... its caught on slower than Google would have liked, but they've shown no desire to stop throwing money at the project.
6) in 2011, 15% of Facebook profits came from Zynga... a game app developer. You know, that one that spams your news feed with ads asking you to start growing wheat in a game called Farmville.
As a company Facebook profits less than $1 billion a year... I'm not sure how they could be worth $75 billion under any circumstances other than a dot com super hype frenzy. Google dwarfs Facebook as a company in size... and all it takes is a couple of bad moves from Facebook on the PR front to allow a foot in the door from someone else who could crush them with funding...
Personal anecdote... chatter within some of my circles of friends indicates that people are starting to boycott Facebook and some are moving to other social media sources that are fresher and newer. So although Facebook is the start of it all and has the numbers of users... you have to wonder: how many of those 800 million log in daily? weekly? monthly?
As a company, they really have little to no assets... just users, or people. The key to their success is trying to squeeze as much ad revenue from those users as possible while making sure they don't run to the next "hot new thing" out there...
As you can tell... I'm less than optimistic about facebook.
I'm guessing they see the money passing and rushed to get this IPO out there to cash in on their fame before their 15 minutes (er, I mean 7 years) are up. Their timing has been less than ideal... last fall would have made a much larger splash.
I have no doubts that this stock will swing huge... up and down. A lot of people will make and lose a lot of money on facebook. My gut is that in 20 years facebook won't be around anymore. This is not one to invest in for the long haul.
P.S. Zuckerberg (facebook founder) plans to cash in $1 billion worth of his shares in the IPO. He claims its to pay off taxes for exercising his stock options...