I forgot to post my impressions here, so here goes. Been playing this, it's fun. I've completed the first two worlds, which took a few hours, and I didn't 100% them, so I'm no longer worried about the game being shorter than DKCR. I don't think the levels are longer, they are pretty lengthy in DKCR. They are probably larger, in terms of scope and verticality and such, and so they can feel longer when going for all the collectibles. Speaking of, I feel like the puzzle pieces are more well-hidden in this, I haven't come across them as easily as before. I think there are also more levels in the worlds, with the secret ones and such, which would make up for having less worlds.
I was expecting there to be some remixes from DKC2, but I think everything I've heard so far has been new material. But that's fine, because this new stuff is pretty good. DKCR was kind of disappointing in the music department, so it's nice to have a DKC game with a good soundtrack again.
So far the game feels pretty similar to DKCR which is both a good and bad thing. It's good because it continues with and builds on the elaborate, well-planned level design, but bad because I completed every little thing in DKCR and know the mechanics inside and out. So there hasn't been much that feels new aside from the swimming. It isn't a big deal though because the levels are still fun.
I'm disappointed that they didn't improve the multiplayer, because I'll be trying to play through with my sister. When we played through the first game, she didn't start to have too much trouble until the sixth world, and by the final world it was getting to the point of frustration. I had to give her an invincibility code in order to get her to complete the game with me. That's something I couldn't do here, so we might not beat this one if we start it. I'll see what the later worlds hold.