Caelesti is an advanced vanilla+ pack which takes advantage of many hidden features that are both vanilla, and MCPatcher reliant to completely change the way that Minecraft is experienced. The pack has a huge focus on custom flora, and fauna, and attempts to improve the many inconsistencies and flaws of the original look of Minecraft.
Many of the biomes you'll find in your world will look completely different due to the complex biome specific colourmaps that are used in Caelesti, as well as unique biome based textures for complex models and custom entities.
Caelesti is an always-in-development project, with new techniques constantly being made available for MCPatcher, and a whole host of features introduced by Mojang with every update that can be changed and improved. To stay up to date with the development of Caelesti, you can subscribe to My YouTube Channel where I frequently post updates to the packs features.