TTYD is a great game. It's a great follow-up to Paper Mario. It's better in almost every way. Filled to the brim with charm and a great art direction. Emphasizing style over cutting edge graphics (when it was released) which has helped this game age very well. The Switch remaster does do some interesting things, but I personally feel the hyper shiny and reflective filters they have added to the game clash with the great art direction of the original release. These feel like cheap ways to justify selling the game at full price. Not every change to the remaster is bad though. They have some great flourishes to the graphics, such as the added paper cut-out animations to when an object moves through water. These feel very faithful to the original art direction and do legit look great. Aside from that, I think the game looked overall better in its original release. They do add some small quality of life improvements which aren't bad by any means, but they do nothing to improve the bad "Trouble Board" side quests. You still need to take on one trouble at a time and all of these side quests are mostly tedious backtracking that rarely give you a good reward (there are a few exceptions such as one giving you a new companion for your journey, but for the most part the rewards for these rarely feel worth it. Though some are actually pretty fun distractions, such as dressing up as Luigi to talk to a fan).
Still overall, while this doesn't really bring anything new to the table it's still great nonetheless. The combat is still very firmly the same thing as Paper Mario. The only new mechanics are around the battle screen being a theatrical stage. Here there is an audience that can grow as you level up and perform well. The added benefit to this is gaining star power faster to let you use your powerful spells. The stage also has some negative effects. Such as audience members being able to chuck things at you or the stage props attacking you. This rarely transforms gameplay but it does add some variety to the gameplay. And more importantly fun flavor!
The charming writing and art direction are what elevate this game. Like with Paper Mario, the characters are all silly and charming, with the exception of the main villain, resulting in plenty of amusing and sometimes funny moments. Some of the best parts are related to Bowser bumbling about between the end of chapters always a few steps behind Mario. This is cleverly subversive and unconventional for a Mario game, excluding the original Super Mario RPG that put Bowser in your party. Still as the second best subversion in the franchise with the relationship between Bowser and Mario I'll still take it. Bowser ends up acting as comic relief very effectively. Always blundering about. And some of his interludes are direct call backs to the original Super Mario Bros from the NES! This doesn't feel like shameless nostalgia bate, instead it's a tasteful and fun homage. Another fun bit are how you can interact with Luigi in Rogueport between chapters and he has his own fictional adventure that he will tell you about. Always accompanied by a new companion who almost always begrudgingly contradicts most of what he says. I'll say no more about these interludes because they are best experienced going in blind. But they always stayed amusing and fun. Giving the game lots of personality.
Princess Peach is given some agency even as she is again captured (kind of a pity that only Super Mario RPG did something different with her character arc by letting her join the party). Her interludes are borderline kind of creepy. She is being spied on by an AI who has fallen in love with her after watching her take a shower... so yeah kind of a dicey relationship, and it does effectively act as the same relationship Peach had with the Star from Paper Mario, just more creepy! Still these interludes actually help you learn the layout for a future Dungeon which is kind of a neat way to incorporate that into the design, creep factor aside.
Something else that doesn't feel conventionally Nintendo is also Rogueport itself. It's a run down and bleak harbor full of criminals and has a hangman's scaffolding as the centerpiece to the town square. Aside from this, the game isn't too dark. You do visit a place called Twilight Town where everyone talks about how depressed they are (to be fair everyone they knew and cared about were turned into pigs by a joker-esque evil ghost so yeah that wouldn't exactly raise the spirits!). It's a well designed hub. Like with Paper Mario, it also gives the game a pseudo-metroidvania design to it, where you unlock new parts of the hub town as you unlock new power ups and companions. Which makes returning to the hub feel fresh and engaging as you try to figure out what new areas have opened up to you. It can also be very satisfying after unlocking a new power-up and realizing you can now snag a previously inaccessible item! Making the player feel clever.
Like with Paper Mario, the power scaling of this game is low which I find appealing. The highest damage I did by the end of the game was 15. I like how this keeps damage and combat comprehensible. While I get the appeal of seeing 9999 damage pop up, it loses context at some point. Leveling up and power creep are low and it works because the game is designed around it. You still feel progress and more powerful as you progress. The badge system returns and it is good. They don't really shake it up too much and there are a lot of the same badges from the first game in this one. Not really sure how many new vs old, but it definitely feels like a case of "if it ain't broke don't fix it." Which fair enough. I do still like the badge system.
Companions serve as the other form of combat variety and customization. Each companion does fill a similar archetype as they did from the original Paper Mario, but they give them fresh designs and personalities. Goombette, like with Goombario, does feel like objectively the weakest companion again. Tattle is useful as a skill, but I found myself actually preferring not to use it. Not a bad thing to have it as an option, but other companions that are more clearly combat and traversal focused outclass her sadly. There are definite winners in the companion front. Yoshi and Bobbery are easily the best in terms of combat. Though Flourrette (I think that's her name) has a great ability that can instantly kill almost every enemy of the game, making her the best for the Trial of 100. So it is kind of a shame that earlier companions feel more and more useless as you progress. They just get outclassed by better companions. You still will end up using Koopa for some puzzles, which forcing you to use companions for world puzzles is a design that returns and is well implemented. Traversal isn't nearly as complicated as it is in any main Mario title, but it's still enjoyable.
Another fun new addition are the black chest curses. This is a really fun and clever way to introduce a new power-up for Mario where he is "cursed." They shake this up a bit but this is a fun and flavorful way to introduce new mechanics into the game. Feels creative.
There's a lot more I could say, but I think it's best to not include too many spoilers. The levels are thematically varied with a great art direction. The world design and hub loop in and open up shortcuts to make traversal easier and keeping the central hub, Rogueport, feeling fresh as new areas open up due to new power-ups and companions. There is a lot of backtracking in the game, in some dungeons, in almost all the side quests, in a few of the main quests, and while this padding feels unnecessary since the game is already pretty long, it doesn't sour the experience. It's still a great game and a lot of fun.