I havent purchased the prog. but have used it when it was free. VM is a good raster to vector conversion tool. Anyone that has done raster to vector conversions knows most trace prog. are only as good as what you feed them. All companies doing conversions are using some sort of prog. and then doing node editing and cleanup.
I've used the online services quite a few times and I have to say their engine offers better vectorizing than corel & illustrators. Another great program that has a bitmap to vector tool is inkscape.
P.s. The new desktop vector magic edition is overpriced.