Since the closest thing to a demo is the pre-order/kickstarter only Toybox, I really have no idea how it would play. I've never played Banjo-Kazooie. I never had an N64. More nostalgic to me are SNES platformers, PC ports of the early Tomb Raider games, and Combat Flight Simulator.

There is obviously a lot of nostalgia fueled hype from the Banjo-Kazooie/Rare fans... but what am I missing out on?

We won't know for sure before the game is out.

a 3D platformer?

A collectathon that probably hasn't aged that well.

But at least it isn't Donkey Kong 64.

With the genre as a whole. Or the very least, Rare developed ones.

Fairly large levels and a million things to collect.

I don't think you can get more literal than that. :)

sorry for the derail

Overall, I'm gathering that it isn't that much that I'm missing. Thanks. Don't worry about it!

DK64 went overboard with the collectibles. It was the metaphorical straw that broke the metaphorical camels back and pretty much killed the genre.