Estimated: It's very interesting this discussion thread. I will give some of my opinions, I hope I understand (and apologize for my poor English).....
Good things: Cinnamon 3.0, I think that how any Graphical Environment, is going to improve with every update. Maybe, do not turn out to be completely polished, but judge best, when Cinnamon 3.1 go out...... Cinnamon ever works best..... I see the progress on the Mate desktop very good too. The Mint's themes, question of tastes only (and they can change very easily).-
The XApps seems to me, a Great Idea, a Fabulous Idea !! Not only for the Linux Mint universe, the good point it's that you can use in any Linux !! Great point..... It can be the best Project of the Linux Mint house (after Cinnamon, of course). The would my only doubt with the XApps, whether they same ones work only in environments GTK (Cinnamon, Mate, XFCE, Gnome) only ??, or if also they work in environments QT (Plasma 5, KDE 4, LXQT) ??
Bad things: The fact that Linux Mint comes with Systemd for default !! Badly point and very bad decision..... Where is the user's freedom ?? Why Linux insists on running Systemd, knowing that is not very reliable and is giving more problems lately ?? It would be wise to have two editions, one with Systemd and other startup with another system init (SysVinit or OpenRC)..... I know it's more work, but it would be take a free choice.-
And the topic from which the new .iso images, come without codecs, also it's another bad decision. Many people were choosing Linux Mint, exactly for doing the life to him very easy, thing that, one throws for land with this decision.....
When there goes out Linux Mint's 18 final version, with Cinnamon and Plasma 5, I will take a look around, but I think will be keep with 17.3. Best Regards.-
Linux Mint 17.3 Cinnamon
Linux Mint 17.3 KDE
Manjaro Linux XFCE (OpenRC)
Pisi Linux 2.0 (Beta)