MTL Star is definitely my favourite sandwich place in Montreal. The place is very simple and that is OK. It is ideal for take out, since the music can be a bit loud sometimes. But who cares? The sandwich is great!
Make sure you try the Classique, but then other options are great too. My favourite is the Radical with the sauce Mistral, which is spicy. Really yummy! If you're really hungry, it is the place to go! You won't be disappointed.