I didn't install stable flavour CSSU until a week ago.
I wasn't to bothered about the portrait mode. Was happy with DrLaunch.

Since I have installed the portrait is really useful and the UI is smoother.
I don't seem to need a reboot every week now, the OS fixes are really noticable.

I have had no trouble with any apps/widgets since installation
Pleased I installed now, can't wait for stable OMP.
Also a better portrait keyboard would be useful.