So, I just wanted to share my general experiences. I was there last week with my two sisters - only two of us chose to use the service, as my other sister isn't much of a ride person and chose to start her pool time earlier... First, I have traveled the third week of April 3 years in a row, the previous two times with my family. I thought it would be busier this year, due to Easter, but it didn't feel busier. If anything, the crowds felt lighter and I felt like there was more availability for "good" FPs later in the day. I don't know if it was due to longer Easter hours or what, but just wanted to say that since the FPs were kind of driving what we did, so not sure how it would change during a busier time like Christmas or whatnot.
I understand why people might feel like it's difficult to deal with the schedule when there are unforeseen delays (as there always are!) but we loved just knowing the schedule and being able to plan/decide our next move with that in mind. There wasn't that feeling of - hey, if I go to the restroom or into that store, will I just miss the bus and half to wait? If we had a delay or a better option, we just planned for the next one or reassessed, but we didn't feel like we were wasting time, if that makes sense. I also don't know if I'd spring for it with my whole family - not so bad when you're just paying for yourself - it would only be worth it if my kids had the stamina to go to the next park, since no matter what you do, you're adding a bit of time. Normally we're a mid-day pool break family, but as the kids get older that will probably evolve.
So anyway, we spent two mornings at MK and did our first three FPs there. I was able to get Rock N Rollercoaster FPs both days right during lunch (around noon) for the 1-2 range, so it made hopping very easy and worthwhile for us, as we had used our Tier 1 HS for Toy Story. On one of the days, we then got a Great Movie Ride, then a Soarin' so we decided to hop to Epcot. The other day I think we just did the RNRC and went back to the resort. I feel like we used it 4xs (including twice one day), but I'm drawing a blank on the other time...in any case, I felt like it added to our spontaneity, but that may not be the case during a peak week or if you have a larger party...