Sure. I ate there this past October when I was exploring middle-of-nowhere local haunts along coastal Georgia.
First, it's difficult as anything to find in the dark. Make sure you've printed out a detailed map in advance or have a GPS with you. I drove in circles for about 30 minutes in pitch dark with no cell reception before finally backtracking appropriately to this place. You can really get lost out on all those branching coastal marsh roads. It's even difficult to find once you get to Sunbury itself - no streetlights, unpaved dirt paths as roads. There are some signs for Sunbury Crab. but they can't be seen in the dark. It's basically at the very end of the line.
The structure itself is very rustic and beautiful. It's open air, an elevated layout with everything on the "second story" on tall pilings. Live oak trees overhang the building, and it's surrounded by sabal palms and right on the marsh. You absolutely cannot beat the "al fresco" setting.
I found the food itself to be okay, but not out-of-this-world good for fried casual seafood. I ordered the shrimp and oyster platter with baked potato and fries, and a caesar salad to start. The shrimp had a nice sweet taste to them, but they weren't quite large enough for my preference, and frankly, a bit rubbery (meaning left in the fryer a bit too long). The oysters weren't that good - they were small and the batter covered up most of what was there. Still, I had a great time there hanging out with locals, watching a football game, drinking a sweet tea and beer, and watching dusk disappear over the coastal marshes. It's an experience you can't get anywhere but along the Southern coast.
I've attached some photos below of Sunbury Crab Co. Sorry for the poor quality, but it was DARK.
Just speaking on comparative food terms - for casual seafood in that area that maintains a very local vibe, I would recommend Speed's Kitchen in Shellman Bluff (also an absolute nightmare to find in the dark) or B&J's Seafood in Darien, GA. All three places (including Sunbury) use local seafood, which is an absolute prerequisite, but the latter two cook it better. B&J's also does it on an amazing buffet spread some nights (I think Friday and Saturday).