As I remember in all previous versions of AE, I was able to actually watch, frame by frame, my composition being rendered in the comp window. Now, when I render in AE CC 2015, there's just a static image of my comp. The rendering works fine and everything, but sometimes I like to monitor my renders frame by frame. Is there a way to turn this back on?
This problem causes can not work with CC2015！
You can work in CC 2015 and then open that project file in CC 2014 to render it. That's what I do.
It also lets you use multiprocessing to render which CC 2015 also doesn't have.
I like the improved expression handling and snappier interface in CC 2015, so I prefer working with it, but CC 2014 renders faster (on most projects) and, as you mention, you can preview it while it renders.