My story: I recently bought a new iPad and it came with Apple TV for 3 months. I installed it on my PC (bigger screen) only to find that that got rid of music on iTunes the first time I opened iTunes afterwards, as others have found! I would not have done this if I had realised.
However, I have been caught by iTunes freezing for a while, so thought I'd give Apple music a go again since it now seems to be being forced on us. It works more or less for me (although froze once!) however I found that when I tried to sync my iPod shuffle (yes some of us still use such things!) it was recognised by Apple Devices, but would not sync any songs onto it - I assume this is because they are not physically on the PC under Apple Music folder. (They are in the iTunes folder, but the two don't talk to each other it seems.)
Therefore I have reverted back to iTunes for the moment. For me the instructions above worked, although I also had to sign out of iTunes and back in again for it to load up my Apple music (i.e. to see music from cloud as well as files stored on my PC.)
I would be willing to move to Apple Music once the sync issues are solved.