I'm a big time DKC fan -- the original is still my #1 favorite game -- so I figure now that I've spent a lot of time with DKCR I might as well post a few thoughts.
Level design -- very impressive. Some real inspired, "wow!" moments and levels in there. In particular, I really liked Prehistoric Path and Music Madness. Both really showed off how far 2D platforming has come since the glory days.
The look -- love it! I think I agree with most people that the silhouette levels really stand out (insert pun here!). There are definitely multiple areas where you just want to stop and look at the lush scenery. Very well done.
The sound -- honestly, not a big fan. I don't know when they changed the Donkey and Diddy voices to their current versions, but for some reason they put me off. And while I think there are some great remixes of classic DKC tunes, most of the new music is not memorable and the technical quality seems fairly poor compared to other platformers, even Super Meat Boy.
The controls -- I know this has been a polarizing and heated debate in this thread, but sadly I have to pile on here. I'm not a Wii hater or a waggle hater at all -- I think motion controls are great when applied right. But with DK having more momentum to his movements than he ever has, I found myself avoiding the shake unless completely necessary because I never felt confident that I'd get it to work properly. Blame it on the game, blame it on me, blame it on the Goose ... but I really struggled here. The world 7 boss highlighted this big-time for me.
The verdict -- I think this was a great playthrough, but I don't see myself coming back to it to 100%. I think it has really inspired moments, and I'd like to see DK Return again. But please, please, please at least give me the option to try a non-shake control scheme.