The Fuji Japanese Steakhouse on Route 9 has the most amazing sushi and sashimi I've ever had. The freshness and creative presentation are definitely worth the visit, as is the impeccable service.
I haven't tried the hibachi yet, but friends have told me that it's comparable with the sushi in terms of freshness and quality.
The sashimi sampler for one has approx. 20 pieces of different fish, each one fresher than the next, and is beautifully presented. The tuna martini appetizer (pricey at $12.95) is worth the splurge.