I dine at Pho Thanh regularly for the last 5 years and it is THE BEST Vietnamese restaurant in Northern Arizona (there are two just as good in Tucson but that's beyond the scope of this review). I tried so many other Vietnamese restaurants in the greater Phoenix area and none comes close.
For those who really dig for real Vietnamese food - Try their sandwiches between Wed - Fri. They usually run out of the sandwich supplies after Friday. Just remember those tasty sandwiches will make you smell funny for a while...in case you sit really close to a sensitive coworker.
I can't think of any dishes not to try..they are all economical and authentic. If I must complain on something then it would be the meat they use for Pho (the soup). If you want it authentic then you can't ask for quality meats so it's a catch 22. Otherwise, this restaurant tend to provide more varieties of veggies that go along with the soup.
We always get great services here, and yes you have to bring your bill to the check-out counter. And no, please do not keep bothering the owner during the checkout process, you will just end up making other people behind you very pissed off. My ex-boss embarrassed the *** out of the group by keep asking for samples on those "green-looking drinks"...not cool, don't do that.