It has been a few years since I drove I-40 from Memphis to Little Rock, but there are no bad hills or curves. The pavement was not the best, but I heard Clinton helped that. I have never driven to Texarkana.
The roads aren't hilly or curvy. Probably not the "best" pavement but better than I-55 north of Arkansas! And Clinton didn't help anything in Arkansas!!!!!!!!!!!!! To Texarkana you'll probably run into some road construction, but not too many places you don't get some construction. Road construction going on around Little Rock/North Little Rock also. But roads are getting better. Arkansasan for 50+ years.