When a project gets buzz because it's explicitly stated to be a spiritual Banjo sequel, I think it's only natural for a few of those to exist.
-Art style. Yes, it's only 3 months, but the art and first world show a clear art direction that deviates from the Banjo games. It can be tweaked, but we definitely already have a feel for what they're going for. Naturally, people will voice their thoughts.
-Clothes/Design. It's true we don't know the characters, but it's also true that some people find the designs plain, and others even find them completely unappealing. And of course there are those who want continuity with Rare's other clothed designs. Should you demand it be changed? No, but I don't see why people are surprised this is a hot topic when the build-up to their reveal was done in the way it was. It doesn't seem to be an attack on Playtonic, it's just preferences in aesthetics.
-I didn't go through it all, but wasn't the thread on shadow spots a valid gameplay concern? I agree that it is underestimating playtonic (I'm sure they would have caught that if they didn't build around it), but if it DID end up reminding them of that, I can only see this as a potential positive thing. This one is probably just concern over the change in technology since the N64 days, I think.
Crap like the worlds are too empty, too much backtracking (Uh, what...? Who said that?), or complaining about the world expanding is indeed very stupid this early on. If we had more positive threads over raw discussion and analyzing, I'm sure this place would feel sunnier.
Oh, and screw those people attacking Grant.