There is a new noodle shop in Ngo Thi Nham street which looks very clean and nice, in a big house called Square Noodle(Pho Vuong). It is a bit pricy but it is worth it for the comfortable chairs, high tables, and air-con which is great in such a hot summer.
It's quite a tasty soup in a big bowl served standing on the square plate. There are lots of different options but it seems to cater for western people, due to the price and the look of the shop and the way they cook. The smiling faces from the staff make it quite a nice atmostphere.