The default theme of vbDrupal uses the vBulletin template engine and tries to make it look as much like vBulletin as possible.
Examples of sites using the default theme (all currently run on 4.7, but for 'looks' nothing changes with 5):
http://www.unrealadmin.org/ (this one also uses vbDrupal in the forum environment for the left side menu bar)
http://www.alleria.com/
http://www.spacebuffs.com/
But of course you can also decide to use a more customized theme for the drupal side.
(non-support questions can be asked here, but preferably on the vbdrupal forums because I don't monitor this thread as much as the vbdrupal forums are monitored).