I really did not enjoy this game. I couldn't care less that it's dissimilar to the RPG's. But it's just not a great adventure platformer. Let me start with the positives. While I don't think it was anything crazy, I enjoyed the story fine enough. Most of the writing was at least entertaining, but it has a weird amount of drama that feels half-baked. The music was pretty good, and there was a lot of creativity to the visuals. So here's where the problems start. The game is just REALLY boring. The game gives you MANY mechanics to work with but they are rarely used in an interesting way. Pretty much every puzzle is just "Swap into 3d" or "change into a different character/pixl." The game doesn't combine or telegraph these abilities very well. There were MANY occasions where the solution was to switch to 3d, and the only telegraph was that you were stuck. But often, you wouldn't even realize you WERE stuck until you reached a locked door, and then you have to backtrack randomly trying the 3d ability. Even if you figure it out, it's not satisfying to realize that the solution to the "puzzle" is just to change your ability. On top of that, the pacing is all over the place and extremely bloated. Every chapter is interrupted by a drawn-out bit where you go wander into a different part of town to unlock the next chapter. They aren't fun or creative, they just waste time. Bosses are also extremely easy or monotonous. The quality can vary by chapter to chapter.
Chapter 1: It's fun enough, mostly just a tutorial.
Chapter 2: This one sucks. it's tedious and FULL of places where the solution is not telegraphed at all.
Chapter 3: A decent chapter. Has a good amount of variety to it, and was more entertaining than I expected.
Chapter 4: Actually fun. It has many of the same issues as before, but there's a decent schmup segment and the platforming is generally more enjoyable here.
Chapter 5: Tedious and drawn out.
Chapter 6: Terrible. It's really just fighting the same few enemies over and over and then walking in a long hallway for a few minutes.
Chapter 7: Also pretty bad. It has many bits where it just wastes your time for no reason, and has a bit where you need to navigate through several near-identical cloud areas to find specific items. Very tedious.
Chapter 8: Very long and drawn out, exemplifying every issue the game has. It feels padded, it has simple and unintuitive puzzles, the bosses are boring, everything.

In short, this game is not fun. I'm not the biggest fan of TTYD, but boy does that game blow this out of the water.