The ones actually inside the casino... there is a food court with chain outlets, including Puck Express and Johnny Rocket's, Ben & Jerry's, and Hot Dog Hall of Fame (Nathan's). They are what they are, OK enough chains.
Bar Louie's has great burgers, from what I've heard; we haven't eaten there.
Timbers Buffet has some good stuff, for those who might choose it. But they should avoid the "Old Forge pizza" at all costs, it is awful. Avoid the chili, and the bbq'd pulled beef. Stick to the marinated salads, the pasta, the pierogies (hard to screw up), the hard items like the chicken etc. The sweets look OK but aren't worth the sugar hit. (An aside: I know the buffet chef fairly well, I know her mom very well. She is a very good pastry chef, and rankles at the limits being the buffet chef puts on her.)
Pearl is a sushi bar. We don't eat sushi, so, who knows. Maybe t's good.
Ruth's Chris is the same as all the other Ruth's Chrises.
Rustic Kitchen is our restaurant of choice in Mohegan. We've had most of the menu; IMO it is the best casino meal and value I've had, at any PA or NJ casino. Highly recommended (and on the lunch menu) are the Italian spring rolls, the brick oven pizzas, the baby spinach salad, meatballs al forno, and the arancini. On the dinner menu, the shrimp spaghettini, the chicken & sausage calabrese... really anything is good, but those two are our "go-to"s.