Having tried Five Guys burgers whilst in Fort Lauderdale I was stoked to wander passed the one in Old Montreal the other day with a few friends who were in town.
My experience with this particular Five Guys is similar to those noted below in the sense that the "feel" of the place is spot on, it's unapologetically a burger joint. The staff were professional and friendly despite the fact that they were clearly in the middle of a rush - the girl at the cash was efficient while still being personable.
The burger did feel a little sloppy though I'm not sure exactly what part of it broke it - I think it was just the overall building of the burger. The flavours were all there but it just fell apart (part of that is my own handling of it but let's be honest, this wasn't my first rodeo).
The fries, however, were stellar as was expected... fresh, crisp where they should be crisp and soft where they should be soft. Just add ketchup and you're all set.
You should stop in and grab a burger - I'm a fan for sure.