It's just like going through AT&T. No different, but you get your iPhone faster since you are going right to the source.
I did the same thing when the iPhone 5 came out 2 years ago with the same results.
Tried that. The site wouldn’t work. When going through the Apple site it couldn’t find my ATT account. Tried it over several days. I’m guessing it’s on the ATT side of that though.