I have used them and will not again. They were quite honestly a waste of my time for our summer vacation. I stressed and stressed about touring plans, because I was led to believe on this board that the ONLY way to have a "successful" trip in the summer was to have detailed touring plans. And this is probably true - if your only goal is to see and do it all and cram as many rides in as possible. But we are NOT those people. We are people who are far more content to go with the flow, see what we see, stop and enjoy what takes our fancy etc...
So, if your main concern is rushing from ride to ride, then yes, I think they will be useful. Were they accurate? So-so. We only used them loosely for the first couple days then I literally threw them in the garbage. For many rides their wait times were fairly accurate - however they weren't able to predict the ride that was broken down, which of course kind of threw off the other plans. They grossly underestimate Test Track (they only factor in the ride itself, not the pre-ride design area, or the after-area, which easily adds 30 minutes). There were other discrepancies, I just forget what.
To me, the only "plan" worth making is: book your 3 FP+ for your can't miss rides and ADR. From there, just go with the flow, especially if you're doing rope drop. I mean, I definitely think it's worthwhile looking over the park maps to get a feel for what is where, and I still think the most effective way to tour is to do one land/general area at a time. We did Frontier and Adventure Lands the first day, Tomorrowland and Fantasyland the second day, and then the third day we did a bit more Fantasyland and focused more on meet & greets. Doing RD with FP+, I really don't see Touring Plans that necessary because you can get a lot done in those first couple hours, because wait times are pretty low. I mean it's really just common sense stuff: hit the "biggies" first, do the others after. You don't need to pay money for an app to figure that out. Now, if you weren't arriving until mid-afternoon or evening, I could see needing to be a bit more strategic in your planning, and where the app could come in a bit more handy because every ride will have wait times to some degree and many significant ones. So, the app can help you work around that.
But again, a touring plan can only take you so far. Because they don't plan on impromptu potty and snack breaks, your child seeing a character that they REALLY want to meet, or wanting to ride Magic Carpets or Tomorrowland Speedway two times in a row, or wanting to play checkers on Tom Sawyers Island, instead of heading back for the next ride etc... etc... For me, while I love Disney, the vacation is about our children, and what THEY want, not what we want. So we are very content to sit back and let them take the lead, rather than rushing them (or making them skip) experiences, just so we can get to the next ride.