Recently purchased my 5 at my local Shack. While I didn't have any problems, I was there well over 1 hour for the whole process. I was the only customer in the entire store the entire time, and it took 4 employees to complete the process. Also, be prepared to receive a somewhat forceful barrage of sales pitches on everything from $50 cases to $20 screen protectors.
Overall, no problems (unless you count them opening my 2 boxes before I could stop them) a problem, just be prepared to stretch your patience, and have a strong no ready for the sales pitches.