This is my favorite place to get sushi in the greater Pittsburgh area. First, the staff is so kind and when you're a regular, they remember you and it creates a great sense of community the way they pay attention to their customers.
One of my favorite things about this place is the free "appetizer" of fried wonton "chips" I believe they're called that they give to every table with dipping sauces. Who doesn't love a bowl of fried dough? It's like eating the best part of the eggroll (which, by the way, their egg rolls are also top knotch. I've only ever preferred Mark Pi's China Gate eggrolls more but they are closed now). I also love their house salad with the ginger dressing. Their dressing is creamier than most but is so good you could drink it like soup.
Their sushi is of amazing quality. I've had just about every roll there, and I have never had questionable fish quality and consistently good flavor. I've been to decent places that sometimes haven't thawed the fish out entirely or on the salmon sashimi there's some graying of the fish - never at Osaka. 100% perfect every time. The sushi boats are great for groups as well.
Their non-sushi dishes are delicious as well, reasonable portions that leave you full with maybe some leftovers but don't intimidate you either.
I always get a pot of their hot black tea or a Sapporo beer.