I've eaten here a few times. I can't say if it's the best pho in Vegas - as I've only been to a couple other places around town for pho - but it is delicious.
As others have stated, the broth is a bit on the salty side. I don't mind salty, but it tends to overshadow some of the sweet component of the broth that makes pho unique and not just some generic noodle dish.
I ordered #18, dac biet - which includes rare beef, tripe, and tendon. There was a really large chunk of tendon at the bottom of the bowl and that was my favorite part. I also ordered a banh mi french baguette for one dollar which helped sop up some of the broth.
The place is clean, easy parking, and super fast service (pho arrived less than 2 minutes from order). I'll be back for sure.