"Kirby 64: The Crystal Shards" is often seen as one of the greatest console "Kirby" games of all time. Being one of the few legitimate "Kirby" platformers on a home console for the longest time, many look favorably at this game and have great memories with it, loving its faithfulness to the series as well as the ability to copy two abilities at once. Generally, fans of the franchise often consider it to be a great game. While I personally am not crazy about the game as some others might be, it was still good fun overall.
"Kirby 64" has a lot going for it: it's relatively fun overall, the visuals are still colorful and nice to look at, the music is amazing, and the controls are solid. There are quite a few things that work here, and the game as a whole is pretty well crafted. To go along with that, there's even a decent bit of challenge here, making it feel pretty satisfying when you finally beat the game.
Unfortunately, a few things work against the game: for starters, it's fairly short, and I can't imagine you'll really want to come back to play it many times after your first play. On top of that, the game starts to lose its luster after a while, and while you'll be loving it for the first few worlds, it will get a bit boring near the end.
All in all, though, "Kirby 64: The Crystal Shards" is a safe, good, fun little 2.5D platformer that's worth a good playthrough. Seeing that it's only $10 on the Wii U eShop, that's a great price for a nice, cute, relatively fun game.
Final rating: 7 out of 10 "Good"