I do think Project Mew is interesting in a way. It's something the show to its credit has never really done before.
That might be to its benefit. A lot of fans don't really like the idea of legendaries being treated like quick 'final bosses' that are captured rather easily, and I think it's easier to swallow at such a later point where tons of them have already made common appearances. It's obvious by this point that not every legendary is at the same deity level as Arceus, some are just super rare and powerful Pokemon.
Battle quality, as with most JN's, is hit and miss, though I think Project Mew has been the best showcases for Goh in terms of his trainer development and experience. I also agree that the use of rivals is pretty good, like Gary returning as a mentor rival, Horace being promising but maybe too overly friendly for his own good, and the more opportunistic rival duo who are willing to fight dirty (even if they sadly only appeared very late in). In hindsight though, I'm surprised they didn't try to sneak Lana and Manaphy in there somehow.
The chip quota approach I also kinda like, it gives a way of letting others feel like a threat without having to grind the main character's progress to a halt. They also do a decent job showing that Goh couldn't get through simply on good runner up.
I think it still could use more substance as an actual professional goal, but I think it excells above many previous anime-exclusive ones, having good longevity, building on agency and just being good for character building. It also doesn't feel like a diluted variation of one of the previous goals like the showcases did.