I've used it to create a genealogy and to insert other GEDCOM files into mine. It's pretty easy to use and has a straighforward, simple interface. I've tried all the other GEDCOM apps on VersionTracker - some of which promise lots of snazzy features that never seem to be quite what I want - and I keep coming back to SeeGEDCOMX.

It's not perfect: it's crashed twice without obvious cause (it is a beta); I've had a minor problem when merging two files: a couple parent-child relationships somehow come out "one-way" (e.g. child shows up on parent bio but not vice-versa; maybe due to slightly different versions of the standard?) and have had to fix by hand. Otherwise a solid app.