I went to try out this location for Thai Son 2 nights ago. I'm not sure if it's a new location or not, but it looked really bright and clean - a good sign.
The menu is extensive, offering more than just your average pho dishes (they have broken rice here!). They advertise that they have the best vietnames food in town. Don't agree that it is "the best", but it's pretty darn good.
I ordered the shredded pork and springroll vermicelli bowl. It was huge! Filled with fresh basil and vegetables. My only complaint was that my springroll wasn't filled completely with meat. The end pieces were just pockets of air.
The service, unlike their Coq. location, is non-existent. When I entered, she didn't even approach me. She beckoned from across the restaurant for me to sit. When my vermicelli bowl arrived, it sounded like there may have been a mix-up. Instead of explaining to me, the server hovered over my bowl, arguing with the other server from across the room. When it was resolved, didn't say anything to me, and just walked away.
I would return for some more good food, but I would not expect the same service as the other location.