For what it's worth, I like the special stages in Lost World 3DS. I think the gimmmick is neat (and I'm pretty sure there's an option to control it without tilting too), although unfortunately I hit a wall because they don't give you enough time to beat them.
HAH. "Learning curve" only in that you have to learn to accommodate how bad they are if you want to progess. No, those are some terrible controls. Even the 3DS version feels more natural to play.
Erm, no. If you didn't have it figured out by the end of world 2, it's your fault.
Use of the run button gives you substantial amounts of speed and control. The only criticism I have is that spindash is impractical for the majority of the game.
Don't get me wrong, overall I prefer colors, but the literal on rails levels in lost world felt more skillfull than the majority of colors, to say nothing of the rest of the game.
EDIT: Now that I'm not on mobile, I will elaborate on more of the mechanics.
The multi-lockon system was a natural risk vs. reward system. Jumping high enough to get a lot of hits often leaves you vulnerable due to the momentum you had when you jumped (and inability to dodge outside of completing the attack), and getting the most hits out of a lockon means waiting until the last possible moment to execute, which could lead in failure if your timing isn't perfect, making you lose all your target progress.
This ties in with the split jump functions, and the bounce. The former is probably among the top 3 reasons the game's learning curve is as steep as it is, as mentally programming the two different functions to buttons that serve the same primary action is a bit strange for most people. However, when perfected it gives substantial amounts of player control: the homing attack is your most important offensive component, so naturally it gets its own button, but a lot of the time you wish to ignore your lockon targets, as the double jump gives you substantial momentum if you are jumping into it with enough speed. This actually lets you skip a lot of troublesome sections rather naturally. The bounce essentially replaces the slam. Instead of grounding you completely (or having you slide when held on the ground), it instead gives you back height, and functions as an offensive attack against certain enemies. My biggest complaint about bounce would be that kick is also mapped to it. While kick is moderately useful if you don't want to do a multihit attack against a group of enemies, this one function isn't enough to justify it's existence in my opinion (it's also forced with a few enemies and bosses, but that's really bad mechanic forcing).
I was actually quite surprised how well parkour was implemented. Instead of destroying the entire game, the game designed its jumps with the system in mind, ensuring that it didn't become too easy once you fully learn the mechanic. As the run button serves little purpose while in the air, I see no qualm with mapping parkour to the same button. The most unintuitive parts of the system, the wall shift and wall run, were almost never necessary, and to my knowledge the only time the wall shift was actually required were for a few red rings. Personally, I enjoyed mastering both, as the wall run is really fun to use (it's a shame there are so few good places to use it as opposed to just running through).