I have had both a long and pleasurable experience w/ Aji Sai. Going to one of the schools nearby, I have had occasion to visit frequently. In my opinion, the best part about the restaurant is its Lunch Time Buffet because it's very inexpensive and filling. The menu itself is extensive and provides a great selection to choose from.
Personally, I would recommend the sushi because at this place they make it right. The crunch of the sushi and the authentic Japanese flavours are very refreshing, especially if you're used to eating the refrigerated kind from Metro. Anyhow, I would caution first-timers to be careful of how much they order if they do plan to eat from the buffet. I say this because at this restaurant the policy charges you for any food you don't end up eating. Twice I've been in this situation where I've been too full to finish everything and both times I've had to shove the food into my friend's purse so we could get out free.
Overall, Aji Sai is a good experience and the staff are helpful as well. Bon Appetit!