The new version removed at least six mission critical features, so I didn't upgrade. I could not have written my book in Pages if I was starting out with the new version. Style management, in particular, is crucial.
If you’re a Adobe CC subscriber, you already have access to it. If not, a InCopy CC license costs $240 a year.
http://www.amazon.com/Graeme-Blake/e/B009A0YBWO/
What would be the major advantages? I'm sure there are some, I just don't know much about it.
InCopy makes it easy to add styles that translate well to InDesign. The same is true for tables and lists. I’d say, watch the tutorials Adobe and Lynda.com[1] created.
InCopy has copyfitting features: you can see exactly how many lines fit on one page and how many lines you’ve got left. You can also preview the layout.
[1] http://www.lynda.com/InCopy-training-tutorials/232-0.html
I suppose I should check if the new style management means I no longer need to do this. But there were other features I needed, so I won't upgrade yet. Not worth risking breaking my workflow until I see where the dust settles.