I've tried a lot of sushi places in Phoenix, but this is my FAVORITE!
The best AND worst part about Yen Sushi: they have great specials every night after 8pm. They place a lot of their quality rolls on "happy hour" for only $5! The bad part about that? It's crowded! This is a small sushi bar tucked in a strip mall-type setting, so when they fill up there isn't much room to wait for a table.
It didn't get 5 stars from me because of the service. It's lacking! Even when tables are open, expect to wait at least 5 to 10 minutes before you are greeted. When you ARE seated, refills usually come only when you ask for them.
Overall, this place is exceptional. Sure the service may need some improvement but you can't beat the quality of the food, the specials they offer, and the inviting environment. Give it a try, you'll love it!