City Mapper Vol 1 is the first mapping package I've bought and it certainly delivered what I was hoping for. I am running Rise of the Runelords and my players have gone completely outside the bounds of the adventure, forcing me to use a location of the city for a potential fight that doesn't have a map!
Using Sketchbook Pro to create the map I found the transparent background PNG files worked quite well, the rooms and roofs stretched and squished without trouble to fit the dimensions I needed.
Here is the combat map for Razor Alley, in the town of Sandpoint, that I created with this product. The small interior is a separate map I made for when it becomes relevant.