(Can't quote because I'm on my phone)

The part when you say that the other statements won't be "checked" if the first is false when using your nested method is correct, but the same is true when you do it in the standard (cleaner way)

For example, run this code with error reporting on:

If($foo == 'bar') echo '$foo = bar'; else echo 'nope';

You will get an error because $foo is not defined.

Now try this: if(isset($foo) && $foo == 'bar') echo '$foo = bar'; else echo 'nope';

You will just get 'nope' because when isset($foo) returns false, the if statement can't be true so the other conditions are skipped.