May turn into a rant :D
I'm sure Nintendo was very adamant that Retro make this game challenging, but instead of doing it the right way (NSMB Wii) they've disappointingly gone for straight up trial and error.
In every level there are a number of things that WILL kill you the first time you come across them. Progression boils down to getting to an obstacle, death, trying again, success (sometimes). Then 5 seconds later you repeat this on another obstacle. And it goes on like this until you reach a checkpoint, at which stage you've gone through that section of the level at least 5 times. Now repeat that entire process twice and the level is over. RELIEF. But there's no sense of accomplishment. It feels like my memory is what got me through rather than skill. The minecart levels are the worst. You're constantly on the move so there's no time to think about what's coming. "Oh, so you have to super bounce off THAT particular enemy's head to get across. Now to do the whole thing from the beginning with this knowledge ". The rocket barrel levels are just plain retarded. Leave your finger on or off A for a split second too long and you're dead. This is NOT good game design.
I appreciate what Retro is trying to do with scripted sequences and such but at times there is simply TOO MUCH shit going on. It gives me greater respect for NSMB Wii. That game was no masterpiece, but from a design stanpoint it was hard to fault it. Just pure platforming, simple yet deep mechanics, perfectly balanced difficulty and well thought out level design.
Back to DKCR. Bosses... some them have the most random, confusing attack patterns I've ever seen. The waggle makes for some really frustrating moments too. "Oh shit, I've just landed on this tiny platform with this dude that's on fire and I'm facing the wrong direction and I can't go anywhere else cause there's massive fireballs everywhere! *attempts to turn around, duck, and blow in the space of a millisecond and ends up rolling off the platform and dying instead*
It's a good thing this game is fun when you're alive. Cause otherwise it'd be in the trash >_>