This restaurant has been mentioned on Chowhound several times over the years, including recently in this discussion: http://chowhound.chow.com/topics/901060
Friday evening was my first meal. We were hoping to try the bun bo hue, which is only available on Fridays, but they only make 30-40 bowls per day, and by the evening, they were all out. Fortunately, the things we ended up trying were quite good.
My favorite of the night was the #25 hu tieu nam vang, which others have mentioned. It's rice noodles w/ shrimp, fish cake, and pork, and served dry with soup on the side. It's also served with a soy-based sauce, which is to be mixed in with some of the broth and mixed up with the noodles. It also comes with herbs and bean sprouts (which were slightly cooked already). I thought the overall flavor was great, and all of the ingredients were really fresh. Really worth a try.
We also had #42 com tom thit nuong - grilled pork and shrimp w/ steamed rice. Presentation was nice, flavors were good. It wasn't super special, but it was a well-made version of this rice plate.
Finally, the banh xeo. It probably isn't my favorite in SF, but it was still very good. Crispy, a bit greasy, made w/ mung beans, shrimp, pork, bean sprouts, and served w/ lettuce, mint, basil and perilla.
The main thing I noticed at this restaurant was the quality of the herbs. The mint, basil, cilantro and perilla were some of the nicest I've ever seen anywhere, let alone at a restaurant in the Tenderloin. I asked our server, and he said his mom (the cook) goes to the Produce Terminal every morning, so apparently she's well connected to someone who's growing some really nice produce.
My DC had a fresh lemonade which was a bit too sweet but fine. Service was friendly. This place is very no-frills, but it's nice to have another Vietnamese place to add to the regular rotation.