Mucho puts together a serviceable burrito. It's better than the Taco Bell it replaced (they changed something and while I actually used to like it, I can't say I do these days), and if you are in the food court and have a craving, it will do the job.
Burritos are pretty standard... nothing too special, but not bad either. A little bland compared to some of the better offerings, but not offensive. I wouldn't go to First Canadian Place specifically to get a burrito, but if you're in the food court for lunch, it is one of the better options.