Among the best models/textures for animal mobs, especially in the terrestrial mob category. Better Fauna presents a very consistent feel across the various animals available, highlighting the care by ElCeejo put into designing each creature. Being mobkit based means there is also a lot of potential for advanced behaviours and interactions between these mobs to simulate an proper ecosystem.
Onward to the future
As the title states, it is early days, but I am looking forward to seeing the roster of animals expand until this can serve as the de facto animal mod to populate a whole world. Preferably this would mean biome specific animals, e.g. polar bears in snowy/ice biomes, foxes or badgers in forests, etc. to encourage exploration and give each biome a distinct feel. Though other mods more or less do this already, having a menagerie of 'real world animals' in ElCeejo's style would greatly enhance any Minetest game. If eventually there could be bonus animals for specific Ethereal biomes, that would be a real clincher.
Once the roster is more complete, or as it is developing, the second priority should be taking advantage of mobkit to make distinct behaviours and game-play experiences, establishing predator/prey dynamics and unique behaviours for mobs that affect the world. Animals like cows for example are more dangerous when cornered in real life than in Minetest, Minecraft or most similar games.
Possible improvement to the current mod
One minor point that could be improved would be to add a few different sounds per mob so that they can cycle through them and sound less repetitive. Maybe spacing out their calls more or making them more situation dependant would help too.
I am optimistic about Better Fauna's future. Though it current does not add many animals, each one is well executed.