I was inspired by your post, and needed dinner anyway, so I ended up eating at the Temple Club tonight. The hype is real. I forgot to take a picture of the menu, but my girlfriend and I shared a large Mi Quang, a tamarind beef salad, and a bone-in mackerel and pineapple claypot dish served with rice on the side. All of it was stellar. I checked OpenTable before heading over, and saw so many open reservations that I didn't bother to make one. The place was a little over half full at 6:30 on a Tuesday, so take that as you will. The local press has been all over this restaurant, so I wouldn't worry about their survival, but it's nice to know that the hype has dissipated enough for it to be a snap decision dinner on a weekday.
The mackerel included 2 hefty cross-sections and the tail. The meat was delicious, and some judicious rolling around in one's mouth dealt with most of the (admittedly numerous) bones. I wasn't 100% sold on the pineapple-heavy base, although the peppers (seemed like a close relative of Thai bird's-eye) and onions were fresh, they were overpowered by the sweet pineapple. This, however, is a minor quibble, since the fish itself was highly flavorful and expertly cooked.
The Mi Quang is everything everyone says it is, not a lot of further comment needed. The tamarind beef salad had a funky undertone of fish sauce that soaked further into the meat than I'm used to in these kinds of dishes.
Overall, a surprising and novel meal, but also one that actually fills you up. That mackerel, in particular, is worth seeking out during the drizzly days we've been having lately. It's a different dish, and a different fish, from the budget claypots you find in some of the classic East Bay Viet holes-in-the-walls, which usually consist of catfish or swai with an onion-dominated brown sauce, and are rewardingly hearty in their own way.
This is my favorite new East Bay discovery since...well, maybe since Larb Thai. Unlike any Vietnamese food, authentic or fusion, that I've ever tasted, and this is one of my favorite cuisines. The changing menu is likely to get me back with some frequency, although it's not exactly convenient to my house.
Edit: Regarding the neighborhood, I would advise using Lyft at night (if traffic is an issue, and you're coming from Berkeley/downtown Oakland/SF, try taking BART to Lake Merritt station, which is in a safe area, and then catching a quick Lyft to TC), but wouldn't worry too much about walking from the Fruitvale BART station in the daytime. It's not so much that the residential area is awful, as that some of the surrounding blocks are desolate and dark at night, and it's still East Oakland.