There is not one thing wrong with the fast pass system I've used it without any hassles or problems ever. It's not for everyone sure but it's an excellent well done and thought out system.
And if I didn't get a fast pass I wanted I *gasp* waited.
First I want to say we didn't have any *major* technical problems with the FP+ system ourselves. There were some minor inconveniences, but overall the system did at least work (no glitches, no going down, no losing reservations, etc).
That said, I disagree that it is an "excellent well done and thought out system."
There is just too much "insider information" you have to know to get the system to do what you want it to do for me to consider it excellent and well thought out.
My example is from my friend's trip - they arrived a few days after we left, and I'd planned their entire trip. When they arrived, they discovered their DD really didn't like rides. Like at all. So, needless to say, their plans changed a lot.
My friend texted me one morning that they were leaving MK early, heading to the hotel for a break, then heading to AK. She said they hadn't used their pre-booked FP+ at MK, so I went into the app on my phone (under her account) to change their FP+ to AK. I was hoping to get KS, FOTLK and Nemo. I think the options the app gave me that weren't bigger rides were ITTBAB, Nemo, and PW. I knew she wouldn't like 2 out of those 3, but the "options" Disney gave me weren't any better. It was odd, though, that it wasn't giving me FOTLK and KS even when I'd chosen them, because neither of them had the red text of "FP+ distribution has ended for the day" on the 1st selection screen. And I was booking them as "new" FP+ for the day, completely overriding MK, so it's not like there were conflicting time issues that can happen when you're just modifying FP+. Then I had a memory of people on the DIS saying 2 things:
1. That sometimes there is other availability, and you have to just accept what Disney shows you and then go in and modify the experience.
2. That sometimes FP+ availability was different online than it showed in the app.
So, I went on
MDE on my computer instead of my phone (under her account) and went to modify the AK experiences I'd just booked. After playing around with modifying the experience (both time and attraction choice), I was able to get them PW (just b/c I had to have a 3rd), Kilimanjaro Safari and FOTLK. (FTR, Nemo was available, but FOTLK and Nemo both seemed to only be available for similar showtimes, so choosing one blacked out the other, and I thought their DD would enjoy FOTLK more).
My friend *never* would have known that she needed to jump through those hoops. When she saw that her choices didn't come up as options after the 1st selection screen, she would have thought that they just weren't available at all and stopped there.
That was a good 10 mins or so of working/playing around in MDE from when I first started using it on my phone til I was done on my computer. And that was from my home, where I was only 10 ft from my wifi router and had a great signal. Given what my reception was like in the parks, I don't want to think about how long that would have taken me if I'd been there.
None of that is what I'd call an "excellent well thought out" system. An excellent, well thought out system should show *all availability* on *all* platforms. I certainly would not have known about the above #s 1 & 2 if I hadn't been a DISer. A well thought out system is not one that would require that much insider knowledge.
I'm not saying the system is absolutely completely horrible...it didn't ruin our trip (or my friend's) at all. But well thought out or well executed (in terms of programming/user interface) is definitely not one of the words I would use to describe it at all.