I live in Norman, OK and have driven that way a few times coming and going to WDW. The good-we (a family of 6) saved at least $350 by driving. The bad-there just isn't much to see on the drive from Dallas to Shreveport. It seemed to go on forever, ditto for the drive from Shreveport to Lafayette. (then it gets pleasant for us because SIL lives there and we stop for a visit)
The ugly-having the tv/dvd player break down on any part of that trip. And the traffic due to construction on the bridge going into Pensacola, FL. I'm not sure when you are going, it may be fixed by then-but it took a good hour for us to get across in late Nov.
Seriously though, I would do it again. I love having a picnic lunch at the USS Alabama, showing the kids the ocean, and singing along to countless Disney's Greatest Hits CD's on the way there and back.