Well, hard to tell. The print doesn't show well while zoomed in for me. Best I can say is that from what I can see, it isn't too horribly off from my local ares.

Edit: found a section of the site that zoomed better.

Nah, they entirely missed the Appalachian dialect. It's pretty distinct from what they're calling inland south, enough so that it's recognized as its own thing.

Only part of that is about pronunciation, there's usages and unique words too. Which makes this map all si-gogglin.