Yes -- been using their plan since the 90s. Love them.
I'm going one and only one day this year -- just one day at the MK and I subscribed just for that. Love to start with one of their standard plan, customize it, and optimize it // really cool for seeing what looks reasonable to fit in and make adjustments. We'll probably play with the line app too. I love their ride descriptions and rating by age too. Always helps me decide what we want to do on our minimal number theme park day or days. We usually just do one or two Disney parks per trip, but with expensive WDW tickets, I think $13 is well worth it to make the most of your day.
It's probably not as necessary if you are traveling low season and spending quite a few days at the parks. I'm such a big fan, though, that I got it again this year even though for the first time ever my theme park day crowd rating is only a 5 OMG. Usually I go to parks with crowd levels between 7 and 10, although I do try to avoid crowd level 10 days now.