HIGHLY recommend! My girlfriend and I were visiting Montreal for the first time and had heard the city was extremely bike-friendly. We decided to do a bike tour our first day there to get a lay of the land and explore the city, and we couldn't have asked for a better experience!
We chose the 5-hour tour which included the bikes, helmet, and lunch with a beer at Atwater Market. (We did the tour in April, but looking at their updated website now in July, it looks like the 5-hour tour has turned into the "North & South Tour".) Our guide's name was Catherine, and she was simply delightful. My girlfriend and I ended up being the only ones on the tour that day so we were worried it might be a little awkward, but Catherine was super easy-going and fun (and we both secretly wanted her to be our best friend when the day was done). She taught us so much about the city and we got to see quite a bit! There were also plenty of breaks so we hardly broke a sweat if you're worried about that sort of thing.
10/10 would recommend for anyone visiting the city, whether you're a first timer to the city, or a Montreal native.