I really didn't enjoy it. There are several things in this one that I didn't like, even though some of these are purely subjective. I can easily see how people would really like or love this game, though.
I think what I didn't like the most was the level design. While I think the use of Kirby's friends is a good idea, I found myself not liking it very much. Most of the time I preferred to play as Kirby because I didn't struggle so much to walk around with him.
Several times through the game, there are situations where after crossing a door, you have to react very quickly, because either an enemy is dropping on you, or because you're on a disappearing block that will make you fall into spikes. That's kind of scummy in my opinion, but it wouldn't be as big as an issue if they had implemented the double tap to run, like in Kirby's Adventure.
Compared to the previous game, the final boss didn't do much for me.
And Dark Castle 6 can choke on a cactus.

Imagine Kirby’s Dream Land 3, but it sucks ass.

Okay, maybe that’s a little too harsh. This game has that good old fashioned Kirby charm, with very cute enemy design and ally design! The addition of animal buddies was great in my opinion... or, well, a great foundation, anyway. The enemy names are also very good, and I wish I had encountered “Floaty the Drifter” at a time when I was young enough to be deciding upon user handles.

Unfortunately there’s where my praise kind of ends, as this game is bogged down in a ton of early installment jank that makes a lot of its then-new game mechanics feel more irritating than fun. The fact that you lose your abilities after one hit makes it feel like you have to babysit them if you want to use them to solve the puzzles that let you 100% the game, and they’re so nerfed in boss fights that they feel kind of useless to bring along. I think it’s a case of balance but it just doesn’t feel good!

The animal buddies are in roughly the same boat. The screen real estate is bad enough as Kirby, much less the buddies who have way bigger hitboxes. They give you an extra life bar, but aside from Coo they make platforming kind of rough and some of the ability combinations are really bad at actually hitting enemies... not to mention the enemy that outright one-shots the animal buddies??? Honestly, the game feels kind of mean in places compared to a lot of the series, with pits that only Kirby can escape on account of being too deep for Kine or Rick to escape (and also there are spikes). And man, don’t get me started on the endgame autoscrollers.

Anyway, I probably would be easier on this if I actually played it back in the day outside of renting it once or twice, but I keep comparing it mentally to Kirby’s Dream Land 3, which I did play back in the day and basically takes every concept here and makes it better, aside from perhaps being even more obtuse in some of its objectives. I think I would rather play that game again instead of trying to get the true end of this game.

Frankly, going back to the Gameboy feels like it hurt this title, as I believe it to be the weakest entry in the series, or at least the weakest mainline game. The strange hitbox tomfoolery is back in full form, the Animal Buddies feel like they could have been fleshed out a bit more, and the hunt for the main collectibles to fight the final boss is the most obnoxious and tedious it's ever been in the franchise, with incredibly strict and specific routes to follow to obtain each one. Combine that with relatively bland level design by Kirby standards, and you've just got an unremarkable game. One of the only titles in the franchise I'd call "mid".