I am usually not a fan of buffets. I value good food that's well prepared but most buffets just don't have this as their priority. I wouldn't dare to say JJ has this mission but the food is above your average buffet.
The menu is a good selection of mostly Thai dishes with a bit of Japanese fare like sushi and common fresh fishes like salmon. The Japanese menu won't wow you and neither will the quality of the fish but it's pretty good for buffet standards.
The Thai dishes are mostly hit and a bit of miss. The curries are decent along with the pad thai but their skewers are a bit on the dry side. Beef dishes are actually quite decent here too.
All in all, a good place for buffet but you won't need to hold on to your socks, they won't blow off.