wasabi is small but has a very nice atmosphere. I love sushi and have been to several places in the area. Wasabi definitely beats out Oslo and is on par with Ronin. Both the Yum Yum roll and the Michigan Roll are excellent. Also some of the best miso soup around. I've also went there with my parents, both of whom are not sushi fans- they tried some of the japanese entrees and really enjoyed them, my mom got a beef dish..i cant recall the name, but it was awesome.
I would defintely give this place a shot. Its also right next to all the detroit museums, so its a great place for lunch if your checking out the DIA.