Out of the nice steakhouse's that I've been to in Montreal, this is the best in my opinion.
Moishe's is expensive, but it has no atmosphere and the steak is unacceptably inconsistent for the price. Gibby's has a great atmosphere, with a full restaurant that makes you feel all warm and fuzzy inside with the low ceilings .
The food is consistent and worth the bigger price tag. Servers are friendly and attentive, fulfilling the expectations that you usually bring to a place like this.
They also have great seafood options if you're not in the mood for beef (or lamb, etc.).