Can't say enough good about this place. Admittedly, the location at Boundary & Hastings is a little shady, but not actually that bad.
The restaurant's exterior is a depressing old thing and doesn't give much clue to its quality. Inside, however, the place is surprisingly well-kept, and reliably very clean. I've yet to encounter so much as a smudged window in my many visits here. The bathrooms are mostly original and thus not very pretty, but again, clean is the word of the day.
Nothing I've ordered here has ever been been even slightly short of fresh, and - especially if you're used to chain pho like at Pho Hoa - has always been thoughtfully presented and delicious. I'm a fan of all things spicy, so the hot & sour pho with beef and prawns is a favourite; their beef is always very flavourful and the prawns are big and fresh. By comparison, I find the regular (un-spicy) soups a little tame, but that's likely more a product of my affinity for melting my taste buds than their soup itself.
Appetizers like spring and salad rolls are always good here. The vermicelli bowls make for a perfect light meal on a non-soup day. The beef in the one we ordered was surprisingly thick, but very tender and not overly sauced, with crisp lettuce and shredded carrot filling out the bottom half of things.
If you've never had Vietnamese coffee, here's the place to do it.
The service is genuinely cheerful and pretty efficient, even with a full house. Tea is brought around regularly, but not to the point of being an annoyance.
Whether you're new-ish to Pho or have been enjoying it for a while, Pho 66 is a treat.