Please google on fiesta transmission problems. Also, the NHTSA complaint DB for the 2011 Fiesta shows over 1/2 their complaints are related to the tranny. Ford does have an issue with the 6-speed tranny and a Ford Service Rep on one forum only says it's being investigated. The tranny issue usually shows up within a few thousand miles for some cars and one person is on tranny #3 at less than 10k miles.
The 2012 Focus uses the same exact 6-speed tranny that's been used on the Fiesta for the past year. Granted this tranny acts different but pinging, grinding and stalling issues caused by the tranny is not normal. I'm waiting on Ford to find a solution before buying another Focus or possibly a Fiesta.
In the driveway...11 M2 (mine), 09 Focus (daughter), 02 Miata (my toy), 10 GMC SUV (spouse), 00 Focus (son)