Many common components are included: translation tools, database access, code profiling, encryption, validation, and more.
Extending existing components and adding new libraries is very easy.
Uses the BSD license, so you can use and modify it for commercial purposes.
Benchmarking a framework is hard and rarely reflects the real world, but Kohana is very efficient and carefully optimized for real world usage.
Simple and effective tools help identify and solve performance issues quickly.
Very well commented code and a simple routing structure makes it easy to understand what is happening.
This is an OOP framework that is extremely DRY. Everything is built using strict PHP classes and objects.
There are no code generators and endless configuration files, so setting up is fast and easy.
A very active community forum and IRC channel means that most questions are answered very quickly.
These are some of the people already using Kohana. See more on the Forums.