Till now, i havn't used CakePhp, but i have read somewhere that it is the first frameworks to port the RAD (Rapid Application Development) philosophy.
Due to following features it has become the most popular in PHP programming world :
* It is one of the smallest frameworks available: less than 300KB in a .zip archive.
* CakePHP applications can be run both on PHP4 and PHP5.
* A very useful command line script called as “bake” generate code automatically.
* also have enhanced support for AJAX.