We just got back and loved it, as well.
This wasn't one of our better trips, but it didn't have to do with MyMagic+.
MagicBands worked very well. We had a couple glitches here and there, but nothing that wasn't fixed pretty much immediately.
We had linking issues with
UT tickets that we got fixed on day 1 at guest services.
We never use FP-, but used to this time and put it up directly against FP+. We still hated FP-, and we loved FP+. FP+ times were available all day, and we even booked FP+s a few times on the walk TO the ride. We booked Splash mountain on the walk there from Fantasyland and got on immediately mid day in 85+ degree weather. We only double dipped for two days before we went all out FP+ and left FP- in the past.
We used to glitch for FP+ on the last day just for the hell of it and got unlimited FP+s. FP+ was fine all by itself without using the glitches, though. We still aren't huge fans of the fastpass system, + or -...but the + system worked better for us. I understand the sky could fall in the near future, but it hasn't yet, and we liked it like this.
The thing we did notice with the new system is the FP lines were longer than normal. However, I think that was more about user error than anything. There were a lot of people who showed up too early for their FPs that were stubborn and wouldn't get out of the way. Plus, this was the dumbest, most rude Disney crowd I've ever seen.
The CMs need better training, because if you do have an issue, you get a different answer every time. You're just as well off asking fellow guests as you are asking a CM.