Premier is sort of a joke in that regard - I learned that the hard way with the iPhone 4 preorder/launch and again with this round. Premier gets stuck in whenever they enter it into the system, so often ends up behind some other AT&T customers that might have ordered slightly later - my iPhone 4 order was put weeks behind a friend who preordered the same model at the same time through AT&T's normal preorder system. it doesn't seem much changed in these four years.
In addition, if you want to cancel your preorder, it's often a huge process because their servers get slammed especially hard, where ultimately the only way is to call them and they never seem to be prepared to handle the volume (as opposed to AT&T's normal channel).
I changed my mind and wanted a regular 6, so I preordered from Apple with no issues on Friday mid-morning. My early-morning AT&T Premier pre-order was processing, so I cancelled it. I got an email that the cancellation failed with no explanation. Calling ended up getting me passed around since nobody could deal with Premier orders and I finally go a proper number. Calling that only got me disconnects - I finally was able to get through and got the preorder cancelled. It took forever for it to update, but it reminded me why I swore off Premier once before.
Other than Premier, AT&T has been great and I completely understand that there are some snags that are going to happen when the sheer volume of people want to get new iPhones all at the same time.
