We were at the 'World in December. That was our first and only taste of FP+. Maybe something has improved with it since then, but at the time, I kept thinking 'why'?
Our impression was of it was
It's buggy and unreliable. (It took most of our time before they worked properly)
It gives things they don't want, such as unwanted FP's to things we didn't ask for
It doesn't give things we do want (easy of use, the right FP's and flexibility)
It does nothing that the old 'keys to the kingdom' cards didn't do - at least that worked.
It forces people to plan ahead and to set times, denying them to wander about to rides and to adlib their time
It forces people into using technology they may not want -or even able- to use (I come to WDW to get away from PC's)
It tries to fix something that wasn't broken in the first place (What was wrong with the old system?)
Attractions now have FP+ lines where there was none before - even where there is no need for them
And now, it looks like attractions are being FP+ only, forcing this system down people's throats.