Installation notes for the Mac OS version of Gramps can be found here.
Ranked in these QuestionsQuestion Ranking
Pro Free to download and open-source
Pro Lots of available plug-ins increase functionality
Gramps offers a lot of additional free plug-ins to download to further increase functionality.
Con Difficult learning curve can be frustrating
Gramps is quite extensive and sophisticated, which makes it hard for beginners to learn how the software works. It can take quite some time to discover all the possibilities and a help section isn't present.