I think you know what is ORM, that is why, I want to tell you about ORM benefits!
DRY : You write your data model in only one place, it's easier to update, maintain and reuse the code.
A lot of stuff is done automatically, from the database handling to I18N.
It forces you to write MVC code, and in the end your app is cleaner.
You don't have to write poorly formed SQL (most Web programmers really suck at it, because SQL is treated like a "sub" language whereas it's a very powerful and complex one)
Sanitizing, using prepared statements or transactions are as easy as calling a method.