The Festival is a Doki Doki Literature Club mod where Monika doesn't mess with anyone's personality; instead, the festival goes off smoothly and the club gains a new member. But things don't go very well.
The mod is short; probably about 1-2 hours of playtime. It's nothing terribly impressive and it's very disappointing if you go into it expecting to see any Doki other than Monika in the spotlight, but I think if you go in knowing this and not hoping for something you won't get, the mod is pretty fun. You get to continue messing with files, see some new poems, and work with Monika against a believable villain. MC's interactions with the new member are very fun to watch.
Despite being an intensely Monika-favoring mod it doesn't smear the other girls like Shattered Worlds and Exit Music do. It's more than a little unsatisfying how it robs them of agency (especially the one you say is your favorite), but it's not a fatal flaw in a story this short.
The poor matching of poses and expressions to lines is pretty jarring in some scenes, but I've seen much worse and it seems to get a little better after the beginning. The dialogue is also a bit clumsy and awkward sometimes, but mostly in the poem sharing scenes. In the scenes that carry the plot it's mostly fine.
The average poem quality isn't up to the original game or anywhere near the level of The Good Ending mod, but it's not terrible either. Monika's poems are mostly good. The only poem I was really disappointed in was Natsuki's first, which seems to completely miss why her first in the original game was good and copies only the superficial elements.
I have just one moral-related objection: the secret-keeping. After you restore the file of the girl that Wallace tampers with, Monika says she has to "get her out of here before she sees too much". The right thing to do would be to at least tell her the truth about how she was manipulated by someone she thought was her friend if not tell them all the truth about the original game. Still it's far less offensive than in ABND and Shattered Worlds because at least here there's no overarching malevolent force that the girls really need to know about, so at least the claim that they don't "Need to know" is factually true.
Actually, I somehow just realized that there's a plothole here. It's established that the mod takes place after the original game, and Monika remembers it, for obvious reasons. Sayori was president too; why doesn't she remember? I know that the answer is "because this is a Monika mod", but realizing this makes that fact a lot more offensive. The story makes a plothole to avoid giving a Doki other than Monika any agency.
Still better than Shattered Worlds!
I also don't think the two fakeout suicide scenes do any good for the mod. The story isn't missing anything without them.
There's also two secrets in the game files that I'm aware of:
wallace.chr is a plaintext file contianing a meme.
When Wallace tampers with one of the girls, her file is replaced with base64 data translating to "Get out of my head" repeated a bunch.