A nice change but I still cross my fingers in hopes we get a suite of Apple applications that each have their own function
iBooks
Movies
Shows
Apple Music
iTunes (local music & podcasts)
Oh boy. Separate apps for Apple Music and local music?!?! Please tell me this is not something people are clamoring for. The ability to mix Apple Music with all of my ripped stuff is one of the main things Apple Music has going for it that the main competitors do not (even if they don't seem to get that because they never, ever make that point in any of their marketing, ha).
Splitting iBooks into a separate app made sense (it's not really in the "media" category in the same way as the others), but I don't even want separate desktop apps for movies and shows (on iOS it was a great idea, but that's a totally different beast). Don't see the point, frankly — it's not like you're ever going to listen to music and watch a movie at the same time. And judging from Photos, iBooks, etc., it is unlikely that Modern Apple would bake in the kinds of advanced features that iTunes has into new from-the-ground-up apps (I know, most people wouldn't care, because most people aren't using complex smart playlists or customizing their views or being anal about their metadata, but for the power users, these things are huge). If anything, I want more power user features and customization for Movies and TV, not less, and if they split those up into their own apps, you know they are going to be the most basic apps possible, and in all likelihood will struggle (or outright fail) with regards to feature parity and consistency.
For example, the "Up Next" feature came to iTunes late in 2012 (and the Apple TV around the same time) but didn't make it into the Music app on iOS until June of 2015. It then came to the iOS Podcasts app a few months later in September of 2015, and so far, has still not made its way into the iTunes U app on iOS, where I could really use it. Imagine that kind of thing, but on a much larger scale, because I have no doubt that's the tip of the iceberg of the kind of inconsistency we would get if they split iTunes into four or five apps.
I know iTunes has its bugs and some other UI problems, but I'd much rather Apple put the effort into making those right than just splitting it off into several more apps for them to neglect.