I've been doing Parelli for years and it's by far the best and most complete program I've ever tried. My first Levels horse, who just passed away, was spooky, hypersensitive, impulsive, not very trusting, etc. when I got him and through our journey all that went away. Before he went blind I was riding him bridleless, upward and downward transitions and playing in Level 3, Level 4 in some areas. I never imagined I could have a bond with a horse like I had with him. I miss him terribly but he prepared me well for my current Levels horse. He is extremely dominant, very confident and will test you every step of the way. He was 2 trainers, an equine behaviorist and a college's worst nightmare. He was a labeled biter, kicker, man hater and was said to be dangerous, vicious and unprdictable. Everytime someone had him out in the hallway they would put a metal muzzle on him so he couldn't bite anyone and he would charge at people when they entered his stall, so they ended up putting him out in pasture so no one would have to handle him. He was going to be put down if no one took him. I've had him for a year this week and I've done nothing but Parelli with him since I got him home and the changes in this horse are unbelievable. I knew they would be, I'm a huge believer in the program, but even I'm surprised with how far we've come with as challenging of a horse as he is. I play with him at Liberty, ride him bareback, and I can back him up by his chest....that's a HUGE thing for him because when I got him anytime you tried to touch his chest, let alone add pressure to his chest, he would try to bite (he was whipped in the chest when he was "bad" at the trainer's). So a ton of little everyday things turned into huge successes for us. We are playing in Level 2 advanced/3 and Level 4 in one area.
So yes, Parelli is worth what it seems to be. I think you'd like it if you decide to try it :)