Yeah, having watched it now multiple times, I do think it's perhaps the weakest Visual Works opening in the series. Even BBS, which feels fairly pedestrian and at times disjointed, had the benefit of introducing new characters and plotlines. This one doesn't even succeed at the one thing it would have been good for in adhering to its own set up: bringing all of the existing main characters together in a gratifying fashion. It doesn't succeed as a recap given that it focuses entirely on Sora's actions. It doesn't succeed as a shipper AMV given the degree to which Kairi's contribution is contained and how she's promptly disappeared at the end. It's not expansive or breathtaking the way that KH2 and 0.2's openings (the best in the series imo) are, and it doesn't display the level of imagination, intrigue and thematic coherency that KH1's opening did.
Welcome to the forums! I think that Namine will have a role to play in the game, but the fact remains that the opening doesn't do justice to a lot of the aspects of the series which it should have been a celebration of: it feels more like the opening to a middle installment such as DDD or Re:Coded where there was going to be a focus on some specific character arcs that would tie into the bigger picture. It definitely doesn't seem like a proper representation of the breadth of what KH3 should have to offer.
Personally, I don't like the chess motif (in any context in the series) and the fact that this opening doesn't use a sleeping/waking theme like KH1 and 2 is a big mark against it right from the get-go. But even then, the chess symbolism seems to be obligatory and shallow when there are ways to actually fold it into the broader structure of the game. I mean, if we look at KH3 as a whole, it doesn't really have any resonance with the world selection that we know of, Disney or otherwise, or with the gameplay, or with the way any of the characters think or behave, or with anything other than a cheesy hackneyed way of inferring that Xehanort is a "master tactician" who has been "making plans" and "manipulating events" because he's smart and smart people play chess.
I mean FFS they could have at least used cards, those were already established as a relevant part of the fantasy scenarios in CoM and X[chi].