I've been to Dong Khanh when they were located in Chinatown, then Crescent Heights and now 18ave. It's one of those restaurants that wouldn't wow you with their service or their decor so don't expect much. In fact, they've been shut down before because they failed health inspection. This place is not for the picky eaters.
The food is decent enough for me to come back a few times though. I usually order the Pho Sate there which has a thicker coconut soup base. Not the best Pho Sate but this was the first Pho Sate I had when I was a kid so it's memory lane whenever I have this. The bowl is small, bland and probably not worth the high price though. Try the Bun Bo Chien (I hope I spelled that right) which is a fried cake with egg. Also, try the special noodles with liver, intestines, and unknown parts etc.