Perfect hotel for what we needed.
We're a young couple visiting Montreal for the first time. We needed easy access to the metro, some fun spots we could walk to, and a simple but non-grimy room.
Hotel St-Denis fulfilled all of these requirements. The room was super basic, yet clean and everything was in working order. Totally no frills, but we just wanted a place to lay our head, so it was fine.
The concierge was pleasant to deal with and gave us good advice on where to go for nightlife.
I felt safe in the surrounding area. The Latin Quarter is a short 5 minute walk which was awesome. Note that there is a park nearby that seemed to be full of some interesting characters. It seemed like everyone there was on some type of drug. You can easily avoid the park if that bothers you, but there are so many people in that area that I deem it safe. Great for people-watching ;-)
Overall, it wasn't a bad location by any means. Transportation to spots where you're too tired to walk to is plentiful. There's a rent-a-bike station close by as well which is my #1 favorite thing about Montreal. :)