I love burritos, and have tried many of the places in the city, as well as elsewhere here and in the US. I know there's a stigma attached to "chain" burritos by some, but I don't care, Chipotle is my favourite local burrito.
In my experience, it is almost always dependable for a good quality burrito, with good ingredients, fresh toppings, and will be big enough to satisfy me. Everyone's entitled to an off day, and I have had one or two that weren't as quite good as usual, but they are few and far between. The chicken, carnitas, and barbacoa (though a bit salty) are great. They differentiated themselves from BBoyz and the like by bringing a slightly different taste, mainly from the cilantro rice, I think (which BBoyz now offers as a topping).
There will always be the usual banal arguments about authenticity, grilled vs. steamed, "this isn't Mexican"... but I'm an equal opportunity eater, and I just like when the end result is a good-tasting burrito, built from good stuff.
Chipotle isn't the cheapest, and yes, guac is an expensive addition which I usually forgo now, but for my money I know I'm going to get something that is a good size, and I won't bite into and be disappointed. There are more expensive places out there that certainly aren't on par with the quality offered here. We are lucky that Toronto has many good options for burritos, and I like the variety, but Chipotle still sits at the top of the list for me.