Seems that most are happy about their 09 F150's, but there are a few TSB's out on the 6 speed, most I saw were how the transmission shifted up and down. Before buying any automobile, I highly recommend looking up the recalls on that model and verifying they've been taken care of.
There are other TSB's on the truck, you can find them here: http://www.ownersite.com/tsb/tsbs.cfm/2009/FORD/F-150/
Bear in mind that al vehicles will have TSB's out on them, so don't let the list scare you off, but make sure they've been taken care of, or use them in a bargaining chip in getting the price down.
But as for safety recalls, the truck seems pretty safe: 2009 Ford F-150 Recalls