Being from San Diego, California, I know Mexican food. Despite claims to the contrary, what Three Amigos serves in NOT authentic Mexican. Mexicans don't put Mozzarella cheese on nachos.
And they don't use lime Kool-aid in their Margaritas (that's what it tasted like anyway.) Nor do they serve them in glass beer steins.
The food is not bad, it's just not Mexican. The nachos were edible but not delectable but at least the vegetables seemed fresh. The enchiladas were served as flopped-over tacos: the tortillas were not folded properly as an authentic enchilada would be. They tasted fine though.
This place is located in a little suburban strip mall near a car wash. It's very casual. The service was excellent on a Saturday night and they even had a Mexican guitar player/singer.
If you're in the neighborhood, Three Amigos is not a terrible place to eat. But if you're driving, try Tres Carnales downtown (excellent food but no margaritas) or Julio's Barrio in Old Strathcona (OK margaritas and fun ambiance. We didn't eat there since the Three Amigos food filled us up.)
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.