Nothing as dramatic as the Toronto and Montreal ones, but some smaller Halifax ones. There aren't really any marginal/dead-zone areas that have been transformed from nothingness to high-rises, but some of the downtown-area neighbourhoods have seen intensive enough redevelopment that they look and feel completely different in a very short span of time.
First is Hollis Street and Bishop Street. This one will be a bit more noticeable in a year or two, as another new construction will be erected to the right of the highrise. This is one of the most architecturally eclectic parts of downtown, with a solid mix of architecture ranging from the 1700s to today, but there were a lot of dead zones and derelict bits until recently, and the infill has really begun transforming it.
The building on the right in the first pic was a neat little Italianate number with a brick facade below the siding, so it's a bit unfortunate it was demolished. The area has just recently become a heritage district, so this development probably wouldn't have been able to proceed in the same form today.
And then Spring Garden Road and Doyle Street. A much more significant historic loss (besides this old deco-influenced bank building, there were also some Victorian townhouses on the block on the left side that are gone). On the southeast corner of the intersection, just out of view of these pics, there's a whole block of more modest historic buildings that was just knocked down for another project, by the same developer who put up the building on the left side of the 2019 pic.
This whole area has undergone really, really rapid transformation. Architecturally it's mixed (the loss of the block to the left is unfortunate, IMO, but the new central library on the right has been a huge positive for the area). But the area is becoming more densely built up and livelier, either way.