While Twitter's (TWTR +0.00%) IPO seemed like smooth sailing compared to last year's Facebook (FB 2.79%) 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 (GS 2.76%). They also share which IPO from the class of 2013 is the best long-term buy for investors.