I will be honest here; I found Kirby Star Allies quite disappointing. Sure, it did a lot of things right such as the fantastic final battle (though I personally prefer Planet Robobot's final boss) as well as bringing back old faces from previous games and I personally didn't mind the whole 30 FPS since the game looks amazing, but at the same time, it was a step down from Planet Robobot in terms of level design, difficulty, boss fights (again, except the final boss) and was way too short even for a Kirby game...
Luckily I had the patience to beat it, and even gave Guest Star Mode a shot. It was so much fun, despite my initial disappointment.