An excellent Forbes article written by Hersh Shefrin.  My favorite quotes:

“No investor who bought the stock yesterday and held it to the end of the day came out ahead.”

“original shareholders leave money on the table when they set too low an offer price, because they give up more of the company to new investors than is necessary in so far as raising new funds”

So, in a sense, Facebook’s IPO brought in relatively more cash to the company than Twitter’s.  Nevertheless, as far as Twitter’s future returns: “I can’t tell you the future, I can only tell you about the history.”  For now, I continue with my “ignore” rating on the stock.  🙂