Personally, looking at HellfireComm's playthrough of Lost World's 3DS version up to Tropical Coast (where the video glitched out on me at the boss fight), I daresay people's statements that the 3DS version is better in some ways is.. Arguable indeed, Clefant. The bosses are more impressive on the Wii U version, but actually harder, even if not by much, and aren't as pathetic on the 3DS version. I haven't found any playthroughs that go to Tropical Coast on the Wii U version or beyond (that aren't Cobanermani, who.. annoys me for some reason, his commentary just feels obnoxious) yet but maybe i'm not searching well enough. With how gimmicky people say the game is overall, the 3DS version's thrown a lot more gimmicks in the way of the first three worlds than the Wii U version has.
So Red Rings are required for Super Sonic in the Wii U version and the 3DS version does, indeed, have Special Stages accessible at the end of normal stages (not sure what triggers it; collecting a Red Ring, ring count like the classics, or just doing well enough, I have no clue). .. and the Gyro Controls are godawful, if you don't have a wide berth of movement around you, it's downright abominable and impossible to play properly. Which means good luck playing it if you have some recording gear hooked up to your 3DS.
Sorry for overusing Spoiler tags, I wasn't sure what I should and shouldn't spoil on the game in terms of factors or opinions. Tell me if I should spoiler-tag any of this.