The black sheep of the series as chuggaa probably said early in his LP, and it's true - it's not close to as good as the other two games. But it's still good and there is some depth. It's just a Mario game focused on story... and a good example why Mario games shouldn't be focused on story. This type of story in a Galaxy game though would complement it and really take it to another level... but maybe some other time.
Spoilers will be here, and Miles will be starting his LP as soon as SMI2 finishes (which may take until fall, be warned). Too bad this Pixl doesn't exist:

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One thing I kinda wish there was in this case is a buyable item that goes in your permanent storage (like the Return Pipe), that's like a Challenge Medal in Bowser's Inside Story: in addition to halving attack, something that like halves all your earned points, or in a trade-off, doubles stylish points but eliminates / severely cuts down points for defeating the enemy. I love doing combos in this game but you get so overpowered easily, you start one-hit killing everything and there goes the fun combos! Chuggaa did an amazing combo on Wracktail in whatever video the Flipside Pit was, and some Dark Muths in his Finale pt 1 video that really made me lust for some mega combos again. Challenge Medal would also negate card effects.
The game is just too easy for its own good, Super Dimentio and Shadoo are complete jokes even if you don't use overpowered items like Lovely Chocolate (see my Shadoo video on that...). The Flopside Pit is this game's version PM2 Pit 80s levels, where the curve just jumps and there's chances for great combos even at the 75-90 HP / high attack level you will probably be at when getting there post-Ch 8, but the Pit's confined spaces sometimes make that sadly impossible.
One bit of trivia I did learn from chuggaa's LP: you have access to the map that produces Francis's card pre-Ch 8. If you fight Francis in 8-2, you actually do do double damage to Francis. The maps are a subtle way to provide boss cards after the fights were done, but welp, there's a way to OHKO a boss if you want!