Samsung is not pretty good regarding community support, here's an in depth story from a former CyanogenMod maintainer for Samsung's Exynos4 based devices (S2/S3/Note/Note2/etc) [1].

For example, emergency calling functionality was broken for a long time and has been reverse engineered only recently [2].

[1] https://plus.google.com/101093310520661581786/posts/aoAGK5yo... [2] http://www.androidcentral.com/cyanogenmod-fixes-emergency-ca...