I've just installed on my MBP11,2 (like yours). Working as expected with no issues so far.15.3 beta 3 to beta 4 was 1.15gb unfortunately not working after patching for me abit of grey screen , can see log in box and log in and see dock but not wallpaper or status bar .
Because I have an Ethernet connection, I never unpatch first, so it downloaded the whole thing.
Mouse and keyboard continuity is also working without any issues...