I don't think PNH is the end all be all of horsemanship, and I think there are a lot of different ways to accomplish the same goal, but I did develop an exceptionally strong bond with my mare that I used PNH with. She was a perfect trail horse before that and didn't "need" extra groundwork, and had it not been for the fact that I was intrigued, I wouldn't have done this with her.
That same bond may have been developed regardless of what gentle methods I used with her, it may have just amounted to time and doing something other than just riding (she was very mechanical before that yet anyone could ride her) or just grooming, etc., but all in all it was a very positive experience for me.
She went from being "yeah okay we'll ride" to "hey! what are we going to do today?". She would literally run up to the gate when I went out to the barn, ready to come out and "play". Part of that as well is that we did group activities and changed up what we worked on and where we did it and I think she found it more interesting than just riding in the few places we'd tend to go.
In my 20 years of horsemanship, I wouldn't have ever dreamed of inviting my friends over to have a group lunging session lol, so bottom line, for me, I think the concept of the games encouraged me to think outside of the box a little.