Vectorworks itself generally is stable, vectorscript on the other hand has bugs. We have had to go back to VW sp1 because sp3 was unable to call filled arrow heads using the marker() command. In sp1, the arrow heads were mixed around marker(1) became marker (9) from memory. Sp3, no filled arrowhead at all. Made one of our main tools completely useless.
This current problem is with a script which creates a print view so that multiple sheets can be printed at the same time or sent to a single pdf. Has worked fine since version 9, now in 2008 when there are associative dimensions within the original layers it will create the printing layers fine, but unless those highlevel objects are ungrouped prior to deleting the layers the application crashes when going back to the original sheet. (This happens in sp1 & sp3)
And then minor issues I have with some high level objects when they are copied onto a printing layer using vectorscript look like their scales are incorrect (redraw and redrawall do nothing) unless they are placed on the front most print layer or moved manually.
Moving to Vectorworks 2008 has been the most frustrating upgrade so far for us, and this office has been using it since Minicad 6.
As a note, I have reported that arrow issue to both our supplier and on the bug report page on this website, no reply from either.