Popping back in with some reflections on the Magic Band and Fastpass Plus systems now that I've actually used both...
MagicBands: These are brilliant, when they work. I loved being able to go down to the pool without carrying anything, and in the parks they were much easier than getting the tickets out all the time.We had absolutely no problems with ours at all - used them for park entry, fastpass, charging at shops and restaurants, Magical Express, the works. Not one problem. Unfortunately it seems that is entirely luck of the draw. The longest line we waited in all trip was at guest services. We were just adding a day to DD's ticket, but everyone around us in line was there for MB issues and there were two higher-ups going from window to window to assist with those problems. The cast member we spoke with was visibly relieved that we were there with such a simple request. I really wouldn't want to be a CM in the parks right now... Too many people having too many problems, and too many of them losing their patience with CMs who are in no way responsible for or able to correct those problems.
A couple of minor areas for improvement - I wish they'd add passholder identification and discount programs to the band. It detracted from the ease of use and convenience to have to pull out my wallet for my AP, TiW, and ID every time I made a purchase. I also wish they'd offer (upsell) a band that incorporates a small digital clock as part of the customization process. Wearing the band made wearing a watch uncomfortable, and I'm hard enough on my phone's battery life in the parks (esp. with the new app and FP+) without having to pull it out every time I need to check the time (which is often with FP+).
FastPass+: I have much more mixed feelings about this one. It was nice having certain rides reserved in advance. I was traveling solo with my 5yo, so we didn't have a FP runner and couldn't really do the rope drop stampede. Not having to was nice. And even some of those second-tier FPs came in handy - having a FP for SSE early in the day, for example, saved me the "If we ride now, we'll have to wait in that line. But we can ride later with no wait" conversation with DD, who wants to ride it as soon as she sees it and doesn't realize that's the only time of day it actually has a long line.
However, the tiers remain a major area of concern to me. It was workable, traveling with a newly-40" child who got scared on Star Tours and didn't even want to try Test Track or the mountains, but it would be completely inadequate if I was traveling with my whole family. We also found the limit of 3 too low for MK touring, even in the slow season (and this past week was slow... 60min TSM standby at 6:30pm and 40min at Soarin' at 4:30). Fortunately we had physical tickets despite staying at a resort that isn't issuing KTTWs so we double-dipped there as needed (for Peter Pan and Talking Mickey - we used FP+ for Enchanted Tales, Jingle Cruise, and Little Mermaid). When that option goes away completely we'll be stuck spending much more time in line than we ever have.
I did feel very tied to the clock, which was annoying but no moreso than classic FP with return times being enforced. We sort of made up for it by having fewer dining reservations to be tied to, which I'm not sure is the result Disney's looking for but which certainly saved me a few bucks.
Disney's app is still slow and very hard on the battery, and there is little option to reschedule headliner FP on the fly. They really need to work on their coverage in certain high-traffic points as well... In the queue for Soarin', which my DD liked so well that we rode standby after our FP+ ride, I had no Wi-Fi signal at all. That's a long queue and a known deadspot on both cell carriers I've used in the parks, and it would be nice to have decent Wi-Fi to pass the time.
So even though this trip went as well as I could possibly have hoped, I still have serious misgivings about the entire FP+ system. The tiers and the limit of three might suit touring at the pace of a 5yo but I don't see how it is going to work when touring with family members who actually want to ride ALL the headliners in a single park day.