It is with a slightly heavy heart that I give Oniwa 2 stars, they have friendly staff, a cute little restaurant and a very good location but their food is not worth their bumped up prices (probably due to their location) and in a city riddled with sushi joints that serve similar or better quality sushi for cheaper I can't in my right mind give them the honour of 3 stars.
Saying that however, I should note that on my last visit there I was given a 20% discount (since it was before 5pm) and that really helped my $19 sushi dinner. Disclaimer: I did come in here after having watched "Jiro Dreams of Sushi" so there was no way I was going to leave satisfied regardless.
My miso soup tasted horribly "concentrated", salad was OK but the aforementioned sushi was pretty flaky which I hate, and my green tea was never refilled until I asked it to be when they came to bring my bill.
I would say walk a block or two and check out the other sushi restaurants in the area, there are a couple that are pretty good for a few dollars more though.