I'm a bit of a sushi novice, but my friends who love it really like Shiki and then the one that is downtown on 8th and Willamette...can't remember the name.
Our favorite, favorite sushi place in Oregon is the one in Seal Rock, south of Newport: Yuzen. It's in an old Bavarian restaurant building, but it's fabulous Japanese food.
Just for the sake of adding some info in case anyone searches for sushi in Eugene on the boards: I personally love the Sushi Station on 5th street, by the 5th street market, not too far from the train station. It's one of those sushi rotation belt type places. I don't know how authentic it is, but everyone I know seems to like that place. There's also a sushi place that I like, although it's kinda big on the fried sushi type things (lots of other sushi too tho) is a little place in the open mall strip near Walmart at the end of Delta, past Beltline. (There's a GI Joes nearby, it's to the right of there, small restaurant.)
And I've been to Shiki, though I didn't have sushi there, and it was good. It has since moved to MLK Jr Boulevard, near Coburg Road and the bridge, across the road from Kowloon's Chinese restaurant and club.