I have a sneaking suspicion that the quality and/or freshness of the fish here is very suspect...plus I hate that the employees here litter and leave their trash all over the adjacent park and lot, always appears dirty. However, I got delivery from the Kira sushi in Armonk, and it was much better that that of its Greenwich counterpart.
If you really want top quality sushi, keep driving until you hit NYC.
In Greenwich, you can get very good sushi at Ku, on Route 1, off of Exit 4. I've eaten there a half dozen times, and its been consistent, and much better than the average sushi place. It can get crowded, so if you want to eat at the sushi bar (which only has about 10 seats) go early.
In case you ever have the urge to drive two hours for sushi again:
for a happening atmosphere and very good sushi:
Tengda Asian Bistro
21 Field Point Rd
Greenwich, CT 06830
for phenomenal fresh fish, a lot of which is served sushi style:
Nuage Restaurant and Bar
203 E Putnam Ave
Cos Cob, CT 06807
(this restaurant is NOT a sushi bar, and is quite expensive, but the food is great - worth driving two hours for!)