I stopped by the Raku in Cathedral Heights this past weekend with a few friends of mine. I wouldn't say Raku has the best sushi in DC but I say they're worth stopping by. They also have a location in Bethesda and DuPont, so make sure you check them out!
Except for the fact that our service was extremely slow (could be due to the fact that we were a large group and it was a busy weekend), I don't really have any other comments. Again, this isn't my favorite Japanese spot, but it is a place I'd stop by again!
Hope this helps you figure out what you should order and you leave with a full and satisfied stomach at Raku when you stop by! Let me know how your experience goes.