I haven't been this excited about a fast food chain moving into the neighborhood since Five Guys established an outpost in the city last year.
Mexican food is a rather neglected cuisine in Montreal and don't expect M4 Burritos to help. Instead M4 Burritos introduces Montreal to the infamous Mission Style Burrito which is a staple food up and down the West Coast. The melding of San Francisco hippies and Mexican immigrants during the 1960s and 70s spawned the huge burrito stuffed with rice, beans and a variety of other goodies.
M4 is a fast food franchise so expect fast food quality. Neither great nor terrible it's a reasonable representation of the real thing. Service was OK, prices are reasonable (about $12 for a burrito with drink), portions are plenty big, and the interior is clean and bright.