I'm a bit of a regular here. I have never ever had a bad experience at Zen. It's family owned, so expect to wait a little longer for your rolls, but sit at the bar and chat with the guy making the sushi and just enjoy the place. He's super friendly and will make custom stuff for you if you ask.
The AYCE is a great deal, as it includes 90% of the appetizers as well. I think the sashimi plate is the only exception. Do yourself a favor and order the salmon collar off the appetizer menu. It's a chunk of broiled salmon with just a little salt and pepper that will have you checking and rechecking the plate long for more long after you have devoured every piece. They only get 3-4 of these with each supply order, but they have always had one when I asked for it.
They also have a wide selection of the standard rolls plus some house specialties and weekly "experiments". My favorite, the Amazon roll is beautiful to look at and absolutely delicious. The Hulk roll is fun and tasty to boot, and the caterpillar is another of my favorites.
I have never, in the 20 or so times I have eaten there, had the problems with frozen fish or service mentioned in other reviews here. Understaffed as they may be, you couldn't ask for a friendlier staff. The matron of the family often comes out from working the back and I have been sent home with free items just by virtue of being a friendly, familiar face. Eating at Zen is always a treat for me and my family and we really enjoy each and every opportunity we have to dine there.