A medium to high density neighborhood would be fantastic at this location. People in Canada have this idea that anything over 3 stories is too tall and it will just be an urban jungle.
Here's a picture I took of my "neighborhood" from my unrenovated apartment a few days ago.
In any case, the point is that it's not just bare concrete everywhere. My area isn't particularly attractive but there are plenty of others that look much better. Usually there's quite a bit of landscaping involved.
Yes, there are traffic issues. I'm pretty sure they're mainly related to driving deficiencies among the local population but that's just conjecture. Either way, a development along these lines isn't going to destroy the "peaceful" character of Marion or Archibald. As well, sooner or later the city is going to put some sort of grade separation at that corner and relieve the major issues with traffic. The roads themselves can definitely handle the extra traffic volume.
My fear is that they'll just put up more of the usual cookie-cutter shit. Yeah, it's infill but so what? The land could be put to such better use especially considering that eventually there will be a rapid transit connection right along that corridor on Archibald.