I moved from ATL to DC with a U-Haul truck last year.
My dad and I left his house at like 4:00 AM with the goal of making it to DC around 3:00 PM or so. We were making great time until the SC/NC boarder where we stopped for gas. In addition to spending over $50.00 per tank, the alternator died on the truck. The thing wouldn't start. So a few phone calls later, a repair man showed up, diagnosed that the alternator had indeed died, left to find a replacement, came back, installed it, and we were back on the road 2-3 hours later. This shifted our ETA into DC up into rush hour (aka a nightmare in DC). As we got to about 30 miles out of DC, we were hit by thunder storm AND really bad traffic, so we stopped at a Hampton Inn knowing it would be impossible to unload the truck in the rain, etc. This hotel stop cost me $90. In the end it was a good decision to stop as it took us another 2 hours, from 7:00 AM until 9:00 AM, to go those 30 miles in DC rush hour on a Friday morning!
I ended up complaining about the alternator to U-Haul customer service and how it forced the $90 hotel expenditure. They refunded me $90, so the entire rental cost ended up being only like $300 (not including gas).
I would say that $300 is a small price to pay for such a move if you have the time, nerves, and patience. I would also say that they offer good customer service. But on the down side, their hardware (trucks) need to be maintained better.
Would I rent from them again? Maybe. But I would also look closer into competitors like Penske or Rider.