This is an amazing summary of why I loved this game so much... in fact I love Super Paper Mario and Sticker Star more than the original Paper Mario (N64).I bought PM SS a while ago and didn't like it. Last summer I tried it again and it clicked.
I think the worst about the game is the frustration of going into a boss without knowing if you have the right items to fight it or not. Sure, the first boss you can use any of the two big items of World 1 (Scissors or Fan), and there is a boss in a baseball stadium, so it's obvious that you need a bat; but there are some bosses that don't hint a weakness and one that doesn't have one (which is the easiest of them all, lol).
The final boss is fucking bullshit though.
But the rest of the game is great IMO. I love the tonal shift; this game is much less serious. For instance, there is a toad crying that the wind blew all his flowers again, so being this a sort of RPG and all, you go and turn off the fan, then plant some flowers and the Toad is happy again and you get a price. All nice and good here.
But then, if you use the fan or put it in the museum, the fan respawn, and the flowers of the toad are ruined again and the toad is crying again.
This set me back at first, you are supposed to solve problems, but nope, this game is not about that. Toads are idiots, basically speaking rabbids or minions (I love this) and you are not supposed to care for their feelings.
The battle system is MUCH better than other Paper Mario games, much closer to M&L, which is great, no more nanosecond frame to defend bullshit, travelling is much better, you can go anywhere in seconds which is great; there are shortcuts and warp points in stages (especially boss stages), so you can travel quickly once you learn how to defeat it.
The game seems rushed, but I honestly enjoyed it more than TTYD.
About lack of level ups, this is not true. I'm not sure how it works, but as you progress, you definitely get stronger. The good thing about no stats and levels is that the game is more puzzle like, you can't brute force bosses or enemies. The bad thing is that... well, you can't brute force bosses and need to think, and this is what 99% of mainstream jRPG players do.
There is also something else, you are not supposed to kill every enemy there is, so what I did was attack monsters that had a chance of giving me a good sticker. Also, there are plenty of stickers in stages, so you never run out of them, just hoard those shiny stickers, lol.
And lol at not caring about Toad feelings, that was Miyamoto plan all allong.