One of my favorite places around Gilbert!
I try not to go here when I'm dieting, unless I want a splurge meal... You can get salads that are very low calorie but they won't taste nearly as good as anything with the (decently high calorie) delicious sweet pork! Honestly, I think that going here and not getting the pork is a waste because it's the brightest highlight of this restaurant chain. I typically get the sweet pork burrito, which last I checked is their most popular entree. Get it smothered with cheese and the medium sauce and it becomes a dish to die for!
If burritos aren't your thing, the nachos are also amazing! The chips themselves are just sub par but once they're smothered in meat, queso, and pico they get much better.
The sister company to Costa Vida, Cafe Rio, is different in very few ways. Basically the differences lie in the ambiance and feel of the restaurant (Costa is more beach-like in vibe, while Rio is more Mexican-feeling) and that the pork is significantly sweeter at Costa than it is at Rio. For me, there's no competition and I much prefer Costa Vida - though I've heard that you end up loyal to whichever one you visit first.