My DS has been in the parks all week (age 18) with his friend. They are staying at POP and are testing the Magic Bands. Both were very excited for this trip (all alone...no parents or siblings) as their HS graduation gift. Both have been to WDW over 10 times in the past.
They LOVE the FP+, BUT only because they can use regular FP. From what I am hearing from them:
1. They both "lost" the magic band once. DS it popped off on a ride and he picked it up. His friend, completely lost and had to go to Guest Services at MK to get it replaced. Took about 15 minutes to replace it. They gave them two anytime FP's and they have had no problems with it since then. *Don't ask me how they lost them. I can only imagine.
2. They sleep later, something they would not have done without FP +. Get to the parks armed with three FP+ centered around the park that they have ADR's for dinner. Their FP+ is mainly RnR, ToT, EE, Soarin', TT, SM, SPLM....you get the idea. No character meet and greets or parade viewing spots.
3. At their arrival, they also use FP- to get multiple rides (headliners) for times that fit in.
They have both expressed that they would not LIKE the system if they could not get regular FP as well.
Just pointing out the experience from adult teens.