On the plus side, this is authentic Vietnamese food. The place is packed with Vietnamese so you can bet that you are getting the real deal. Having visited Hanoi, I can attest to how the pho is nearly identical to what I sampled in the homeland.
On the negative side, you don't go here for the ambience or the cleanliness. Don't expect to be pampered by the service and it might get pretty smokey in there from all of the tabletop bbq going on.
If you prioritize the authenticity and quality of the food over all else then you won't be disappointed.