I would not stop at the one in Loxley (I think? whatever one is north of gulf shores basically) during the summer, but in general they are a good place to stop. Bathrooms are clean and even when they are crowded (as long as it's not Loxley in summer crowded), they're plenty fast to get in and out of. If you're on the road and need food, the brisket sandwich and smoked turkey sandwich are solid and don't leave you feeling as disgusted as fast food meals, even if they aren't exactly light/healthy.
I will agree with thekimmer that a lot of what is in the store is just touristy stuff. The one on I-10 in Mississippi is going to be in a pretty sparsely populated area, and I'm curious as to whether they will stock that store more like a dollar general (not in terms of quality; just meaning marketing it more to locals as basically a dollar general alternative to basic needs), as I assume they won't get the tourist traffic that the one in Loxley gets. Even the one in Loxley has some basic store (and even home goods) that don't seem to be overpriced or aimed at tourists, but I'm curious as to who actually takes time to browse it while traveling to vacation, and what locals are willing to put up with the summer crowds to go in there.