Gameplay-wise, this game is very unique: it is pretty much a metroidvania with puzzle and collectathon elements, where each level has different treasures to get, which grant you new abilities or change the structure of other levels, granting you access to new objectives in a non-linear progression (and I was pleasantly surprised that the game never became too confusing, always informing you about the levels to check out whenever something changes in the world map). Unfortunately some sections can become frustrating due to the fact that Wario can't take damage, so you get punished for your mistakes by being sent away from where you're supposed to go. Also, I think the game should have been a bit shorter to complete.
Apart from these two things, the overall experience is very good and I recommend checking it out, I don't think I've ever played anything with a structure similar to this.

The first part of this game (up to the Master Sword and the first Agahnim fight) was 10/10 for me, giving you clues about where to go next but never holding your hand too much, letting you explore freely to find some secrets with the items you've obtained up to that point. The remaining 2/3 of the game were overall a bit more confusing about what to do between one dungeon and another, and I had to check a guide to find some useful items in the overworld (I recommend going for 100% items and heart pieces, because in this game you take A LOT of damage in some parts, especially in the Dark World) as some stuff wasn't that clear, but apart from that every dungeon was well designed and the game in general, although pretty tough, was never unfair. I understand why it is considered a classic.