While Twitter's (NYSE:TWTR) IPO seemed like smooth sailing compared to last year's Facebook (NASDAQ:FB) debacle, Facebook's IPO was actually a bigger success. In this story from Investor Beat, Motley Fool analysts Morgan Housel and David Hanson explain why Twitter should be slightly ticked off with underwriter Goldman Sachs (NYSE:GS). They also share which IPO from the class of 2013 is the best long-term buy for investors.