Sorry, you asked about Curl Keeper too....I use this most days after my leave-in and sealer, as I live in Florida where there are high dews most of the year and I find it definitely helps the frizzies! For me, though, it has no hold and so I don't use it as a stand alone styler; always mousse, gel or jelly on top.
However, since you have fine hair, it may work for you especially if you like a soft look with no crunch. I would say this is a definite purchase, at least to try it. You can use a lot of it and it doesn't hurt. In fact, the only issue I find is if I don't use enough.
2C-3A/ Coarse/ Normal to high porosity/ SW Florida
Cleanse: *CJ Daily Fix, AIA Coco Cowash, Trader Joe's TTT condish, Shea Moisture poos
Condish: CJ Smoothing, Curly Kinks Renew, Darcy's Pumpkin, *CJ Curl Rehab
Enhancers & 2nd day products: *Okra gel or FSG, Uncle Funky's CM, CJ Pattern Pusha
Gels: MGA sculpting, Giovanni LAN, Spiral Solutions FHG, LALSG, *JC Spiralicious