Inkscape stands out as a very good vector graphics editing software package with a breathtaking array of features and functions. Simply finding your way around the user interface is somewhat daunting but gives a clue as to the scope of the development of the project to date and the lengths to which the project has gone in order to create something that is of professional quality yet still completely free.
Vector graphics work in very naturally with mapmaking as the representations of objects on a map are very easily derived from vector graphic objects insofar as they are generally either points or collections of points. The three types of shapefile layers in Qgis are individual points, paths or polygons. A path is simply a series of points with lines drawn between them, while a polygon is an area that has its boundaries defined by points. The shapefile only needs to store the type of object and the coordinates of each point. Because the physical appearance of points (in the case of single point layers) or lines (in the case of paths or polygons) is not hardcoded into the file as it would be in the case of a bitmapped image, the appearance of these can be easily changed on the fly and reshaping a path or polygon in particular is as easy as moving one or more of the points. It goes without saying that vector graphics does not suffer from jaggies when the image is scaled to a different size as it is automatically re rendered to the highest resolution available, thus also great for producing PDFs which are also a vector graphic capable format.
Obviously I prefer to use the GIS rather than Inkscape to draw the maps but I have used Inkscape a couple of times lately to trace overlays on aerial photos and here it was just about as easy to do as Qgis and rather easier than using Google Earth mainly because in the latter case when the output is a KML file, we want the resulting coordinates to be correct and this means we have to try and line up the aerial photo to existing features on the ground as much as possible, which is not always easy to do. As far as the drawing of overlays in Inkscape went, the output was just a picture consisting of the original photo with a layer containing the trace paths overlaid on it. Except for the most rudimentary bitmap editors like MS Paint, multiple layer capabilities are generally available in good graphics editors these days and of course in GISs.
If there ever was a point where maps needed to be hand edited (for example to replace the presupplied captions from Qgis with ones that can be more randomly positioned) then Inkscape would probably be the package of choice for that task. The main issue at present for such functionality is that Qgis's SVG export is not very good, due to an inherent technical limitation of the Qt application framework that Qgis is built on. When I produce maps for publication I generally am using the PDF export to get a suitable graphic quality. Using Inkscape to open that PDF seems to produce a very good quality result almost indistinguishable from the original, so it may be possible to produce a suitable result, but I have no idea if Inkscape can produce a good output when its SVG is exported back to PDF.
