Well, I've only had a couple GMS, I've always seen the GM "give" the group their communal Fixer as a means of making sure everyone is on the same page, and has a reason to be going to the same spot. And I mean to the point that I've started to consider a "personal" fixer a waste of points, since he never gets used.
The other contact types, though... definitely worth getting.
Also, I find Group Contacts to be incredibly useful if they fit your theme. Since one Underworld Group, like the Vory or the Ancients, can provide you with just about any service you need, from legwork to leg-replacement, for less over-all points than several individual contacts.