Umi is a Big Burrito venture (a local restaurant group), which means you're guaranteed to pay a decent amount for your dinner and there's a decent chance your dinner is going to be worth it. Some BB places are worth the cost and some aren't. Umi, happily, is worth it. It's still pricey, so this probably isn't the place to sate your random Thursday craving for sushi, but it is an excellent special occasion place for the sushi lover.
Up a few flights of stairs in a minimalist environment, Umi serves up excellent sushi (and a really nice octopus salad), including some higher quality varieties you can't always find in the mid-range places--toro and uni spring to mind. This is not the kind of place you order chicken teriyaki (and if your date does order this, break up with him/her), Umi takes its suhsi seriously and the waitstaff is generally very helpful in navigating the menu, although I did have one experience there in which the waiter seemed like he was preening about his (legitimate) sushi knowledge. The Omakase is expensive, but worth it. But obviously, you can still have a great meal at Umi without dropping $75+ a head. Excellent spot for a date or a small celebration.