The devil is certainly in the details, and valuations are often overly optimistic... But similarly, I believe there are a few really strong companies that are

The devil is certainly in the details, and valuations are often overly optimistic... But similarly, I believe there are a few really strong companies that are dramatically under-valued today, partly because they (purposefully and strategically) don't turn a profit yet, or because they trade at a very high multiple. Facebook is not one of the companies I spend a lot of time researching (but don't interpret this as me having a negative view of the stock-- I just have "no view"). Taking the time to read filings, as well as any investor materials these companies put out (with a critical and open mind, of course) goes a really long way.