My fiance and I came here while we were staying in downtown Montreal for the first time. We took the Metro to get here (which is nearby). The building is just very interesting and quite unique. Definitely not something I've ever seen that would look remotely similar. There were other tourists walking around here like us. Nothing else really going on here except for the opportunity to ride the elevator all the way up to the observatory. But my fiance and I were too cheap to fork over the $15 (Canadian dollars) per person.
Overall, glad we ended up stopping by here since it is a well known landmark in Montreal (it was our first visit here so we had to do the touristy thing).