Expect to wait at least an hour for service - even if all you are doing is purchasing boxes. Employees are very slow, though generally friendly. Booked a truck online, along with apparently 5 other folks the morning of pickup. Despite apparently knowing that 5 people would be coming in at 10 on a Sunday morning to get their trucks, management had only 2 employees working - only 1 of whom was capable of processing rentals. The other stood by idly while the single reservation-capable employee processed rentals for those of us in line, or anyone who called in on the phone while we waited there. And, the single reservation-capable person also ran out side, drove the trucks around, did the walk through with each customer - all while the other employee just stood there uselessly behind the counter, earning a paycheck for doing I'm not sure what.
Here's an idea for next time U-Haul: perhaps the person who can't use the computer could at least drive the trucks around, or do the walk through with the customer. OR, perhaps you might have more than one employee who can handle reservations. All told, we waited 75 minutes to get our truck, and we were the 3rd folks in line. But of course, our rental time wasn't extended - we still had to return it at the same time, despite wasting more than 1 hour of the reservation standing there waiting to be served.