Found this great video of the Line 1 extension while it was under construction during May 2016. It is a ride through the tunnel and passing through the under construction stations along the way. 

 

Looking at the new extension in Toronto, it shows how funds are not well distributed. While Ottawa is building a rapid transit network for the cheapest possible price, Toronto is living large with uber expensive projects. Though Downsview Park and Highway 407 are within the 5 lowest ridership stations in Toronto, both are absolutely massive and probably cost well over $100 million each (Reece Martin quoted up to $400 million in a recent video). In Ottawa, our three downtown stations, with far higher riderships, were value engineered to death, resulting in narrow platforms, rough finishes and (mostly) up only escalators, with the exception of Rideau, probably due to its depth. Ottawa's downtown stations cost about $50 million each according to Watson in 2012. 

And then we have the single track Trillium and three train airport service.  

Toronto could have roughed-in those two stations for future infills, or built part of the line above ground to save on capital cost. They really need to right-size transit projects, and hopefully that will be the case for the Relief line (though ridership for the Relief/Ontario line would probably justify a full subway with humongous stations).