First, they (almost) always seem to be on time, and often too early.
Then, if you want to get off, don't start for handy little buttons to press. Nope, much cooler than that - you have to pull on a yellow cord that is drawn once around the inner walls of the bus.
Thirdly (I should have made this a bullet-point list), the back doors don't open automatically (which could be an advantage during the winter to avoid having the cold draft over and over again, but could also be a disadvantage for all the unassuming tourists (and new students) that wait desperately for the doors to open by themselves. But no matter how long you wait, they won't open. Unless you press a yellow bar which at first glance resembles a holding post - but it isn't. It's soft and squischy and yellow and you can never be completely sure how hard you have to press it.
While the doors might be a slight inconvenience, the Ottawa busses make up for it by having a bike rack at the front - outside. You can just pull it down, put your bike on, and hope that the driver won't be distracted by having a dazzlingly pink bike in front of him.