Two of us went there (7th & E. Santa Clara) last night, at my wife's prompting. She was a big fan of Saigon 75, which went out of business a couple of moths ago.
Saigon Sushi has now taken over the place, keeping the old decor and furniture, but adding two TV sets. The menu(s) are Japanese, and Vietnamese, as the name suggests.
My wife found that they didn't offer green papaya salad, her favorite Saigon 75 item, so she ordered scallops and broccoli from the Viet menu, and I ordered tonkatsu (breaded pork cutlet) from the Japanese. The waiter sounded like he never hear of tonkatsu (a common dish): I had to repeat the word and show it to him on the menu. After a while, he came back to announce that they didn't have it, so I ordered the chicken katsu out of inertia.
Her dish was not good, undercooked in a not-good way. Mine was bland and mediocre, with odd, non-standard breading that fell off the meat. The service was on the inattentive side, with the three young staff people seemingly more interested in hanging with one another than in keeping an eye on the room and clientele. The TVs were running two different channels (one was sports), detracting from the nice sophisticated atmosphere that the old place had.
We're unlikely to go back. Prices were about the same as the old place (moderate/inexpensive), but the food, service, and atmosphere were not as good. There was a sense of elegance and professionalism that imbued Saigon 75, and it has been replaced by slackness and inattention to detail.
OK, the place is new, and it theoretically might get better, but somehow I got the impression that they were rather clueless and quite happy with things as they were.