I agree with many of the comments here. However, the one comment that always puzzles me is the one about the train station. I actually don't think it was great tragedy that it moved from its original location. While it would have been lovely to keep the train station downtown, I think the trade-offs generally made the move worthwhile. Certainly, bigger mistakes were made. Opening up access to the canal, and the creation of Colonel By Drive, were huge improvements that would have been difficult had the train tracks remained (the Nicholas Street extension to the Queensway was much less of a benefit, and a huge wasted opportunity). With no commuter rail, Ottawa's train station was destined to a sleepy VIA station, so it's not as if the old Union Station would have been a hub in the same way as Toronto's Union Station. Even with the new LRT, had the train station remained it would likely only be one station on the route (and not nearly the busiest) - i.e. Ottawa's version of Wellesley Station.
The replacement train station is a great building in its own right. And being right on the Transitway, it is easily accessible by public transit from the downtown and other parts of the city.
The real tragedy is the criminal underutilization of the old Union Station building since the train station was moved from downtown. In my opinion, that was the much much bigger mistake. And there is no sign that will be corrected anytime soon. At least it has been relatively well maintained and wasn't left to rot.
Don't get me started about building Scotiabank Place in Kanata, though. That was crazy. But, of course, the catalyst for the NHL's return to Ottawa in the early 1990s was a desire by Terrace Investments to expand the urban boundary in Kanata, with a professional hockey team as leverage, rather than being purely about hockey.