Very charming, feels like very genuine experimentation of various different gameplay mechanics. Very short, If I had bought this for full price in 2001 I would've been pissed off.
Some things make it feel like a prototype, like the fact that the yellow pikmin only exist to pick up bombs while the other two types have specific resistances and use cases.
I also really love the lack of any handholding or tutorials, the game isn't hard at all but it very much pushes you to experiment with the things you see around you. The only moment when the game will tell you something outright is if you mess up (losing a bunch of pikmin to an explosion or drowning will have Olimar write about it in his journal at the end of a day)
Super charming! Can't wait to play the rest of the series