We really like it. We enjoy the food & drinks (as PP said, the avocado margarita is a treat). To us it's what Disney dining should be--an immersive experience that's unlike anything we could get elsewhere. It's set up as an outdoor restaurant at night, next to an open air market. It's dimly lit, sort of like you're in the shadows of the pyramid in the background and the volcano occasionally erupting behind it, and the boats are traveling past as you eat. Is it like an actual outdoor restaurant in Mexico? No, not really, but it's a really cool experience at Disney.
My kids really enjoyed the dining experience and the food--my daughter (age 11) recently told me it's her favorite restaurant at Disney. I have heard some people complain on the disboards about how dark it is in there--so warn the adults & kids in your party that it's dimly lit. We did use our cell phones to see the menus better, and I also used my flashlight app to light up my food when I took a picture of it.