Some quick thoughts on this, I have not spent enough time with the previous games for the Super NES so I can't make a fair comparison.
All courses in DKCR are built for speed running, enemies and obstacles have been carefully placed for a rolling maneuver which can be combined with a jump as soon as Donkey Kong touches an enemy. This results in a longer jump and the momentum can be maintained by bouncing off additional enemies. This is really fun, but it's a shame that some of the attention to detail and other touches are lost when you're blazing through the game.
The game also gives the impression that elements from the foreground and background are trying to hinder your progress in different ways. Airships shoot cannonballs to knock out platforms, in another course you have to find cover behind rocks from incoming tidal waves. A welcome feature and fun to watch.
The physics are slightly heavier than Mario games and they feel just right for DK.
They have struck a nice balance between regular platforming courses, mine cart races and rocket barrels - you rarely play more than two of the same type in a row.
I find myself coming back to this to improve a speed run or collect KONG-letters. The incentive here is to complete as many levels as possible to unlock PRO courses! These really show what kind of creative talent that the developers at Retro Studios possess.

I clocked this in about a week over Christmas, with all the secret what-not unlocked (I didn't bother with the time trial stuff though - ridiculous difficulty to get gold medals on that).
I've played DKC1 and 2, and really don't like that approach to platform games - memory tests, barrel timing, overly harsh difficulty, trial-and-error hidden stuff, etc. etc. All those elements are present and correct in Returns, so I didn't really enjoy it as such.
However... it is incredibly slick, and visually great. Co-op mode adds a lot also. So if you can stick early 90s platform game design I guess its fun.
I think the joy of speed running diminishes once you have the golds. I wish there was a leaderboard to inspire competition, YouTube is surely where this aspect of the game will live on.
How did you get on with the motion controls for rolling?
Yeah, I didn't have so much trouble there - it was annoying once or twice, when it didn't quite register at the time you expected. It wasn't a big problem at least.
I think the last two 'temple' levels I enjoyed the most, as they pushed the difficulty to the point where it was basically a speed run, and the levels were well designed enough that you could see where you were going wrong, and incrementally improve. It was too much having the whole game in this mode though, for me. I was missing NSMBWii.
I loved the look of the silhouette levels as well. Have you seen this great concept art?:
http://www.nintendoeverything.com/58383/
Its a shame bits of the game didn't look more like some of that.
I know the two or three levels you are talking about! Everything appears as a unified silhouette until the object moves so there are plenty of opportunities to conceal enemies or traps. The last level made clever use of fog, this is one of a few levels where you have to slow down and wait for a platform to reveal itself.
Yeah, that art is excellent
Some of those environments are spot on. This is on the other hand very colourful but I'm sure it would have taken them ages to finish the game with stylised graphics.
I've played NSMB on the DS, does the Wii version switch things up more?
The Wii version is a big improvement, but its hard to say exactly why... a more balanced progression, slightly better level design, that sort of thing.
Also, multiplayer works really well, better than you'd expect.