Douglas Brown has discussed the advantages of using a PHP framework in his blog. If you're new to the world of PHP frameworks, his post provides a concise list of the benefits you will gain. One of the key benefits he finds is:

"MVC or Model- View- Controller is a well-known design pattern that demarcates the database and business logic from the presentation layer. This results in simple, clean and understandable code."

Of course, not everyone agrees! A spirited discussion is currently under way in the comments section of his post. Take a look, and put in your $0.02!