I'm a bit saddened that most people don't seem to like this because I really do. On my first listen I was like "eh, okay, this is a comeback i'll skip" but as I listened again I appreciated it more and more until finally - I love this song! It's just so fun. I'm a rather casual Le Sserafim fan but to me part of their identity is this slight goofiness, Spaghetti, Celebration, Boompala and that trailer of Eunchae falling down some stairs is how I got to know them so I love seeing them carve out this unique corner of the K-Pop sphere.
The main thing about 'Celebration' is that it's FUN! It's not supposed to be a deep song that you listen to for the convoluted sound and lyrics. I can't watch this video without laughing and feeling happy and how can a song that makes me feel that way not be good?
The best comparison for me is like every JY Park track, every song is just so FUN and CATCHY and you just need to relax and not overthink it to really enjoy it. That said I do think they'll regret adding that head-spinning move to the choreo when they bring this on tour, they'll all come home wearing neck-braces, lol.