I just beat the game last night and I thought it was pretty good. The normal battles get old and repetitive, but the boss battles are a lot of fun. Plus, you don't have to rely on stickers/cards or find things, which were one of the worst things about SS and CS. I feel like this game is a step in the right direction. Again, I know we'll never get another rpg Paper Mario game. They've said over and over that it's not where they want the series to go. Though, that was because Mario and Luigi was the rpg series at the time so who knows.
Combat aside, I feel like the world is fun to explore and the characters are fun. Sure, there's a lot of generic Toads, but they have some Toads that have character and personality. Also the game gets kinda dark at times and there's some parts where there were jump scares and it actually got me. Plus it keeps a lot of the charm Paper Mario is known for and keeps the humor from Color Splash, which was the best part of that game.
I know this is probably heresy to say, but I think I would rate Origami King higher than Thousand Year Door. TYD had two main chapters I liked plus some minor things in other chapters, but there was a lot in OK I really liked. I don't want to go into too much detail because I don't want to spoil anything, but there were some points where it felt like I was playing a classic Paper Mario game. At least, in the way things happened in the over world, obviously not battles.