Ultrafine is Photo Warehouse. They have long been known as a supplier of ULF films cut to size from master rolls that they used to buy from Ilford and graphic arts films. They usually have good deals on short dated color film from Fuji.
As for the source of the film, Ilford isn't selling its own films under private labels anymore (though Harman is coating different emulsions for other brands); Kodak is significantly more than half a century old, as is Agfa I believe; and Efke doesn't make a 400 speed film of its own. That leaves Fuji, which makes Neopan 100 and 400, and sells some private label film, and Foma, which makes 100, 200 and 400 speed films. My guess would be Foma, since they coat film on a blue PET base, which is kind of unusual, and Ultrafine makes reference to "the latest state-of-the-art film base."
If it's Foma films - heck yeah! They're great! Only problem is with 120 film, the base curls like mad and is a bit of an issue when loading film holders in a scanner. But if you print in the darkroom, at least on my Omega they're not more difficult to handle than anything else, at least not much. The 400 is lovely, haven't tried the 100, but hear good things.
One thing though, if it is indeed Foma, it's strange that they don't offer the ISO 200 emulsion. But since it'll be available in sheets too, it's an interesting proposition.
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh