More or less like every other U-Haul I've been to; you'll get what you need but it is going to take forever. As long as you don't have any plans for your trip to be speedy, you'll probably do just fine.
On my most recent visit I reserved a truck online but later wanted my dad to be the driver. I've driven a small moving truck and a couple of large cargo vans, but I really, really hate it and my dad doesn't mind in the least so I figured why not make him do it? When we arrived they were able to switch my dad's name over to the reservation but still charge my card.
Getting the van and returning it went smoothly and kept with the theme of taking a long time - the man who helped us check back in was super friendly and chatty with us and everyone else within earshot; great to see a smiling face but it took about three times longer to get settled up and inspected than any other time I've returned a rental vehicle.