It's AWESOME!
Seriously, it's like the 1990s again. There are so many hidden goodies in each stage! However, I'm not fond of three things so far:
1. DK's physics when he does a roll+jump. It's so fast and has such a long trajectory that it's very difficult to aim and time.
2. DK is no longer invincible to enemies while in the middle of a stomp somersault. In the original games, when DK/Diddy/Dixie/Kiddy would jump on an enemy, the propelled 'somersault jump' after the stomp had a very forgiving hitbox and some invincibility from certain directions. In this game, you're only allowed to stomp the enemy directly under you. Because of this, I'll be in the middle of a stomp session and one enemy will be juuuuust a bit too high and "Ooh!" DK gets hit. :\
3. Waggle! I despise having to 'shake' the controller to do the roll (but I do like using it to score extra points when at the goal). I don't like that there was no Classic Controller scheme, and am restricted either to analognunchuck/wiimote, or controller sideways. There was no reason to do it that way when Nintendo has the extra buttons of those other peripherals.
Aside from these, the game is awesome. The bonus stages are a treat, the locales are beautiful, the enemies are new and weird (though I miiiiiiisssss the Kremlings... ohhhh where have they gooooone!?!?) and the animations are nice and fluid.