The function returns a raster file of either actual relief (values are meters above sea level) or rayshaded relief (created via highly recommended rayshader package).
The raster is 5084 by 3403 cells, meaning each pixel is about 90 <U+00D7> 90 meters. It works the best at level of country or regions, at the level of a city or lower it may be somewhat grainy.
Due to package size constraints both versions are stored externally (and a working internet connection is required to use the package). Downloaded size of the rayshaded raster is 8.4 MB, actual raster is 31.4 MB.