It's great once you hit the actual destination. I'm sure an actual full-on road trip is fun, because there are multiple destinations along the way. But the actual time in the car is absolutely awful, especially when you have a lot of stuff and a lot of people (i.e. your family) in the car. My family just spent a week in North Carolina, which was great until we had to go home.
It takes about ten hours to go one way, although, considering all the stops we take along the way (and how lost my dad got), it took us about thirteen hours each way.
Being stuck in a car for that amount of time is enough time to drive anyone a little mad. You're stuck in an enclosed space and you can't move. I can't even read in the car for that long without being sick. I suppose I could suck it up and deal with the car sickness reading in the car gives me (I did towards the end, when I was especially desperate).
Road trips make you desperate for entertainment as well. My activities were not that varied. I slept, wrote in my journal and took pictures out the window. From time to time, I looked out the window, which was either highway or Southern landscape depending on where I was.
By the time I'm done with every road trip, I practically run out the car. My legs feel very stiff and very tingly and it takes a long time for that to change.
Overall, road trips suck. I would prefer any other mode of transportation any day.