We were there last week, the first week where all resort guests were part of the test, and used the bands for everything they were supposed to do but for payments (never had good luck using the KTTW for credit charges and the charges being correct at the end, so didn't want to try it with the bands).
Overall, we thought they were fantastic. Not until we used them did I realize their benefits. Honestly.
None of the horror stories were reality for us. The only issue we saw was that TSM had all FP+ booked one day prior. I see the concern there, certainly as more guests start to use it.
We found booking FP+ ahead of time and the ease of changing experiences or times a breeze with the app. It provided flexibility and actually made the trip that much more enjoyable and stress free. I know, blasphemy! We stuck with the 3 FPs a day and didn't "double dip" with regular FPs, which we saw many people with bands on doing (and thus putting extra burden on the FP system than ultimately will be intended). Entering the parks with bands was easy (and yes, no turnstyles with strollers and one family member in a scooter for medical reasons made entering the parks nice and quick), using them for FP+ access and room access all worked great. Once on, we never even noticed them.
The only suggestion I would have is that if you want to change an experience, it will only look for other experiences with availability for that exact time you had previously booked. It would be nice if you want to change an experience that it would show you all available attractions and then let you select a new time if desired. I also realized that my parents, who were traveling with us, found the whole thing a little beyond their comfort zone and without us 'younger' folks to make and change FP+, etc. that they may not have fully enjoyed what FP+ and MM+ had to offer.
I'm sorry, this is reinventing the wheel to replace it with a new wheel.
Lets run down "benefits" for the end user. (I will bold the areas that the new band/RFID system allows that the older system did not)
KTTW card (non RFID, no bands, the old system)...
1) Charge to your room and an assigned credit card that you set up online
2) Enter the parks and use it as a park ticket
3) Use it as your room key
4) Integrate with your Disney Dining Plan
5) Utilize the Fast Pass system (though paper tickets worked fine for that as well)
KTTW RFID card
The only benefit added is integration with PhotoPass.
Band
1) Charge to your room and an assigned credit card that you set up online
2) Enter the parks and use it as a park ticket
3) Use it as your room key
4) Integrate with your Disney Dining Plan
5) Utilize the Fast Pass system (though paper tickets worked fine for that as well)
6) Integration with PhotoPass
7) Disney can track your general movements using the Bluetooth LE tech
8) You can wear it on your wrist
9) You get to carry it when your kiddo decides they don't want to wear it on their wrist
I used the bands, I liked the bands, I have nothing against the bands...but they are not nearly as "groundbreaking" as people make them out to be. They are an extension of a largely already existing system (which is why integration has been a gripe)...and the major focus really should be on MDE, and not the bands.
MDE, and the modification of how the FP system works is the real news...