I generally used - or tried to use my MB - so I'm not a MB hater by any means. In fact, long before WDW had them, Great Wolf Lodge had wristbands, and many times I suggested them whenever I filled out a WDW survey.
That said, many times over my Magic bands didn't work properly. I don't think the problem was the bands themselves, but an error in how WDW had listed my identity in their system. In short, sometimes the bands worked for me, but often they don't, starting with my first MB. I made 3 trips to the front desk to get it fixed, which was time consuming. Our trip ended before it was resolved. My bands would work for park entry and FP, but nothing else.
Having to go to the front desk multiple times to get a problem resolved is rather time consuming, and sometimes = an outsize hassle. It might = missing an ADR or FP, or visiting the front desk while everyone else naps. So they nap, and wake up refreshed.
Sometimes CM's are pretty nice, and they'll even offer some small compensation for the lost time.
Other times though, explaining the problem is a huge hassle. Some CM's think it is impossible for WDW to ever have a glitch. Those CM's make reporting a technical problem a miserable experience: accusing me of theft or something nefarious. And those CM's refuse to try to fix the problem. Another fun experience is a CM hinting I'm too dumb to use a MB. It didn't matter how many times I said my companions' bands worked just fine whenever we traded.
So then what? Wait in line again the next day in the hopes of getting a different CM? Be THAT person, and ask to speak to a manager? Suffice it to say, reporting MB problems have sometimes been a less-than-magical experience.
Mostly, I just gave up and put up with it, because that is less aggravating.