First of all, I'm a daughter of a Sushi Chef so, yeah, have a good idea on what's good sushi.
quality of the fish used in the sushi and sashimi was good but the chefs who were making the sushi put too much rice in the rolls so I felt like eating rice rolls, not sushi rolls. Also, 90% of sushi rolls served were tuna (the cheap tuna) or salmon. so if that's your fav fish, go for it.
There was sashimi but very competative and once gone, took them forever to get more.
crabs legs were small and little too salty for me. oyster, too scared to try.
A lot of stuff was not on their buffet and had to be ordered separately (charged separetly too) so to actually have a very satisfying meal there, you need to pay buffet price + more.