I agree that you really can't tell anything about the street experience at this point. What you can experience feels great. I think it will be really incredible when all the public plaza and walk areas are open. I love how it accesses the city easily - that is one of the things I've always loved about Canada Place. You can just walk right to it from the downtown core.
Regarding your question about other North America convention centers, the San Diego convention center is nice, though it is a bit older. It sits right on the Ocean and has great views of Ocean and downtown.
But I really love the new Washington (DC) Convention Center -
http://www.dcconvention.com/. It's about 4 years old at this point.
It is a completely different experience than Vancouver's will be, however it is really well executed. It is the first extremely large Convention Center I've seen in an urban core that seamlessly integrates into the surrounding urban street-scape. The New York Convention Center, by contrast, is right in Manhattan; but you feel like you're on an island and have to cross a major major highway just to "connect" to the rest of the city - and it isn't that great an area to begin with. In DC, they put a portion of the center under-ground in order to keep the scale of the building in synch with the surrounding neighborhood (DC has very strict height limits). So you have essentially a 6 or 7 story building, with 2 of them under ground level. But even in the lowest levels, it is still open because of the super high ceiling heights and numerous site-lines up and out for natural light and views of the sky. All the cross streets still connect across the site as well. They created these great wide interior public plaza pedestrian crossings over the streets with windowed views to the neighborhoods on either side. It also has the nicest interior spaces I've ever experienced in a convention center. Every space, including the meeting rooms, have high ceilings. There are huge windows everywhere you look, and large public areas with nice furnishings, expansive walls of exotic woods, unique lighting, and tons of unique public art throughout. It's like attending a convention in a spacious modern art museum.
If the new Vancouver Convention Center interior spaces are as promising as the exterior looks, it will be a great place for folks attending as well. Can't wait to experience the view from those windows overlooking the North Shore.