One of the better AYCE sushi places in the downtown area - Obviously it's not going to be the absolute best quality if it's all you can eat, but it's the best of its type.
I've had 2 large gatherings here, and both times they were able to accommodate us relatively well - I booked for 18 people for my birthday on a Friday, changed it to 23 people the day before the reservation, and about 27 people actually showed up, but they were really accommodating and managed to make it work, even though the place was really busy. The service was also great for a 27-person party, they split us all up into small groups and they managed to get all the orders right.
I recommend Aji Sai, but would recommend making a reservation before you go, as it gets pretty busy. l'll definitely be returning!