A spectacular finish elevated it, but ultimately it lacked a certain something to bring everything together.
Ash vs Leon was the driving force behind the entire plot and turned out to be a very basic rivalry involving two dudes who saw themselves in each other and wanted to have a great battle. Fun, but not the most compelling rivalry Ash has ever had.
Every battle in the PWC had to be framed as obstacles on the way to battling Leon, but the show never stopped and examined why it was so important for Ash or why Leon regarded Ash as such an interesting challenger. The battles along the way lacked narrative weight, with the one exception being Ash's mini-rivalry with Bea, but even that was built on a flimsy losing streak. Once Ash overcame Bea, it was a procession. Raihan challenged Ash by saying it wasn't enough to want to fight Leon; he had to want to beat him, too. Unfortunately, it came too late.
The Masters 8 was nice, but again lacked a narrative significance. It leaned heavily into the meta-narrative of Ash finally facing off against legitimate Champions and scaling heights he never had before, but Journeys itself does a supbar job of selling you on how big these battles really are. For Ash, it was just another tournament, no bigger or more important than any other. Most of his dialogue was claiming he was going to win and expressing how much fun he was having. He barely converses with any of the other competitors.
For all of Ash's accomplishments, he came across so incredibly flat throughout the tournament. The battles were enjoyable for the most part, but we had all these interesting characters in one place yet nobody had anything remarkable to say to one another. There was a flicker of something when Cynthia said she'd retire after the tournament, but it never ignited into anything. Hell, Ash never even knew this was a thing! And then it's gone, just like that.
There's something to be said about Ash's progression as well. He goes from Champion of a fledging league to best trainer in the world, overcoming Steven, Cynthia and Leon back-to-back-to-back, very quickly. What needed to happen was Ash struggling the higher up the rankings he went, but they did the exact opposite to that. Ash struggled early, but swept his way up the rankings and chewed through the top level trainers. It felt like they lowered the power level to meet Ash's, rather than elevate Ash's power level in a more believable fashion.
Cool idea, happy they reused older characters and gave some love to Iris, but I'm left feeling it could have been so much more than it was.