Finished Cuphead in about 10 hours. Really great game if you like some hardcore boss-focused platforming. There are 17 bosses (-ish... one of them is a somewhat variable boss rush of up to 10 simpler bosses), 6 more standard platforming levels and 3 special challenge levels. The main mechanics are jumping, shooting, charging up a super meter for an extra powerful attack and parrying (which means hitting jump in midair). There's a bunch of weapons, special attacks and charms you can buy.
The boss design is really good (reminded me of Hollow Knight). Most of them really require you to learn the patterns and focus on dodging and parrying instead of playing primarily offensively.
And of course the art style and soundtrack are 11/10.
Oh and 5 or 6 of the bosses are side-scrolling shoot-em-ups.
I don't know, it's about what I expected. And I only finished one boss level and one platforming with a perfect score. If I wanted to get all achievements I could probably easily sink another 10 hours into it.