I don't "hate" it (100%ed it, in fact), but there's a few issues I have with Kirby Super Star Ultra:
1. The CGI cutscenes. Eugh, why? Kirby has this dead-eyed stare in the cutscenes, and compare that to the pixel art in the tutorial where he grimaces at the narrator.
2. Revenge of the King is the only new levels. As much praise as the bosses/combat get, the levels in the game are great. Whether they're like an adventure with distinct sections and a boss at the end like most levels, or even just a series of interconnected rooms like in Great Cave Offensive, they're all fun to play through. It's sad that they didn't expand upon that type of thing.
3. The True Arena kind of sucks. The limited healing makes it almost impossible for me to get to the later sections without using a "cheese" ability (Hammer/Stone), which goes against how Helper to Hero encourages you to use the different powers.
Though it's a worthy purchase; except for the 1-cartridge multiplayer aspect, all of the original game is there and as high-quality as ever.