anyone been? is it nice? is it open all day?
No, it's not open all day and I found that very odd. It's plunk out in the middle of the upper floor walkway, too. (Well, to the wall side). It's not large at all.
If you want sushi on Disney property, head to Puck's on the West Side. It's made properly, right there in front of you...
It's downstairs as you first enter the cafe section of the Puck's on the West Side. Just to the right is the actual sushi bar, and there are bar top tables in that section too. They do a very nice job, actually. (And we all know how fussy Ol' Tink is). They'll even use rice paper if you don't like the seaweed wrapper (I do, but I know some folks just can't stand the taste of it).
I would. Or go at an off time. I'm not certain they take reservations for the sushi bar, but I'd give it a go, just to be sure.