My dentist recommended this place to me five years ago and every since then, I keep a keen ear to any of her recommendations as Shimagamo is the best sushi I've had anywhere. I've had sushi in CA, NY, TX and HI.
The fish tastes fresh and the portions are generous. One piece of advice is to eat at the sushi bar rather than one of the booths, assuming you are having sushi. In my experience, sushi tastes better served as soon as each sushi piece prep is done rather than waiting for the entire sushi order to be completed. This place has the best Unagi and an awesome Escolar (which I haven't found anywhere else.) The Suprise Crazy Roll, served with a sweet wasabi sauce, is always on our Sushi order.
The only con is that this place is pricey, but they do have a daily 5-7 happy hour that contains some great options. However, the best stuff is usually not on the happy hour menu. Also, this isn't a place to have Sake bombs. It's a very low key atmosphere for those just looking for an excellent meal. You'll likely notice early on how many folks are regulars. I was told this was the spot where many Japanese baseball players come to have their Sushi.
The restaurant is very non-descript. It sits in a corner of a shopping mall and is easily overshadowed by it's neighbor C-Fu Gourmet.