A year or two back, we went to a small branch of a sushi place called Garnell in Heliopolis that friends had repeatedly recommended. It was by far the best sushi we have had in Cairo, but as it was all the way in Heliopolis and there weren't any other branches, and as such, we never made it back there. However, the name Garnell began to pop up again and again as new branches began to suddenly open up all around Cairo.
Now there's a branch in Zamalek, which is much closer to where we live, we jumped at the chance to go there again. As before, the sushi was clearly a notch above other sushi sports in Cairo and the menu was sufficiently wide and varied.
Cairo is certainly having a sushi boom, and while this has given us many new sushi spots, not all of them are good. However, Garnell certainly is and seems to be quickly earning a reputation for being so. Next time your thinking about sushi, I'd fully recommend giving Garnell a go.
There are several branches, but I have only been to the one in Heliopolis and Zamalek; and can only attest to these two branches, although I'm sure the other branches are just as good. You can also check out Garnell on their Facebook page.