My issue with the group finder is that it picks out the possible dungeons for you. For those of us going for 100 % quest complete, it makes it tough to not be able to start up a group in the LFG tool.
The tool should be wide open in not limiting your possibilities. Really I would like it if the devs looked at the GW2 LFG tool which works really well. The user can create a group for any instance, and people looking select the instance they want to go into. The tool is fast and gets players doing the content they want to instead of requiring you to sit in a zone spamming because the tool does not allow you to select something.