I'm a professional Graphic designer who spent 50% of the time using Adobe Illustrator being the other 40% Adobe Photoshop and other 10% in different stuff. For Photoshop I already found the perfect replacement in Pixelmator but....
The first time I downloaded the demo I had really high hopes for VD but that soon came to end. The catchphrase says SIMPLE, INTUITIVE POWERFUL. I grant the first one 100%. The second one has some things that are hard to grasp, LAYERS to name only one. BUT the third one, sorry, but definitely not. I really tried hard to complete a Pamphlet that I started in Illustrator and I challenged myself to do it in Vector Designer. I don't know what are TweakerSoft's plans for the future, but so far version 1.5.1 barely accomplishes the necessary things for a very basic job. I'm not talking only about the results, I can get a pamphlet done in Microsoft Paintbrush (not being arrogant), but VD's user experience is really poor. The selection tools are really limited, layers are deficient, color swatches restricted, vector manipulation inadequate at best, no real SVG compatibility, the list could be endless. The job can be done but it would take 2, 3 or 4 times longer than Illustrator.
Probably the objective is that, "vector illustration for the rest of us", in that sense VD is accomplishing an outstanding job. But for a serious professional tool, better look somewhere else. If Inkscape didn't use X11 that would be a real Illustrator contender, at least in the Mac OS platform.
I gave VD 2 stars, they are not bad, but they have a loooooooooooooong way to go before I can call VD at least a decent application.