I guess I don't understand these complaints, if the platforming is solid why is the ground being an empty floor on a casino such an issue you and everyone else seems to raise a flag with ?
The foundation of a good platformer is twofold. You are absolutely correct that the controls need to be good. But the level design also has to be up to snuff. If the mechanics have nowhere to shine, then the mechanics are wasted.
These are just my observations based on decades of experience. I've got standards in mind when I look at new games, especially ones that are claiming to be bringing back an old style that I've played more than almost any other. It's all well and good if they want to make a 3D platformer with collectables again, but I'm seeing things that look wrong to me that a 15 year old game by many of the same people got very very right. So while I'll be okay with something that is good, I'd rather have something that is great.
If I see dumb mistakes I'm going to be doubly harsh because the team took money based on their pedigree. The level of expectation set was to deliver a game that was (hopefully) at least what Banjo-Kazooie was. So for better or for worse, that is what they're going to be judged against. And I don't think it is a problem of nostalgia or bias to have issues with core issues such as level design and mechanical fidelity. If anything is to be judged, that is it.
I see a game with somewhat bland levels that look too big and unfocused, leaving the actual gameplay to appear unrewarding. And how is that any better than the handful of mediocre 3D platformers that have dropped in the time since the genre was at its peak? I want something sublime. If they could do it on the N64, my expectations are gonna be about there.
Also, I guess it is worth noting that I haven't had a platformer to look forward to in a while. Especially one that might be really good. So I'm going to want to talk about it, even with limited information. Take it with a grain of salt, like you say: the game isn't even out yet. I'm hoping I am wrong! And yet... I can't confidently judge much else in this world, but dammit I seem to have an eye for some of these video games, and I just can't shake this feeling based on what I'm seeing. :\