It doesn't hurt that it's a mile from our home (actually that's probably a good thing considering the margarita situation), but Leticia's is one of those local gems of LV. Everything we've had here is excellent. Be careful with the spice... It can creep up on you. BUT. It's obvious from the mouthfeel of the spicy food that they use extremely fresh ingredients (habanero, green chilis, etc).
Maury is our favorite bartender (we normally go in the middle of the week). If you're going in the evening, plan to get there early as there is usually a wait.