Not sure why this place has such a bad rating, it is just like any other Lee's and its in the heart of Las Vegas Chinatown. If you can tell me a better place to get a Vietnamese sandwich, then perhaps I could see why you might not like this place but even then, the sandwiches here are awesome.
Whenever I go to a Vietnamese sandwich (Banh Mi) place, I always order the grilled pork sandwich (thit nuong). This is not to be confused with the BBQ pork sandwich which is made out of the red Chinese style pork meat. The grilled pork is pork marinated in a concoction of lemongrass and various herbs that give it a great rich but fresh taste. That along with the toasted baguette, pickled carrots, radish and serrano chilies make an awesome sandwich.
FRIENDLY TIP: If you're feeling a woozy hangover from the night before, which can happen pretty often in Vegas, grab a Lee's sandwich and take a bite. I've learned that nothing calms my upturned stomach more than toasted, fluffy bread. Oh and grab a Cafe Su Da (Vietnamese coffee) for the drive home - that coffee was made specifically for champs. :]