Handing errors in my code using Exceptions

I was wondering how many of you use PHP ErrorException (or just Exception) to manage errors in your scripts. The way im managing Errors/Notifications/Logging is just really messy, and I was looking for an efficient way to clean it up.

I was thinking that maybe I could just throw exceptions from the Models or Libraries if an error is encountered, as opposed to just returning false.

Just to give an idea of what I mean by using the exceptions with notifications..

PHP Code:

<?php
class App_lib {
    private static function _display_notification($type, $message)
    {
        echo strtoupper($type) . ": {$message}\n";
    }

    public static function add_notification($message, $type = 'info')
    {
        if($message instanceof ErrorException)
        {
            self::_display_notification('error',"{$message->getMessage()}; Code: {$message->getCode()}; Severity: {$message->getSeverity()}" . print_r($message->getTrace(), TRUE) );
        }
        elseif($message instanceof Exception)
        {
            self::_display_notification('info', $message->getMessage());
        }
        else
        {
            self::_display_notification($type, $message);
        }
    }

    public static function something($a)
    {
        if( ! is_numeric($a))
        {
            throw new ErrorException("The value $a is NOT numeric..",123,456);
        }

        if($a > 2)
        {
            throw new Exception("The value $a was greater than 2");
        }

        if($a === 2)
        {
            return FALSE;
        }

        return TRUE;
    }
}

$val = 'a';

try {
    if(App_lib::something($val))
        echo "Value was apparently 1!\n";
    else
        echo "Value was 2\n";
}
catch(Exception $e) {
    App_lib::add_notification($e);
}

/*
 * Result..
 * $var = 'ABC';
 *      ERROR: The value ABC is NOT numeric..; Code: 123; Severity: 456
 *
 * $var = 3;
 *      INFO: The value 3 was greater than 2
 *
 * $var = 2;
 *      Value was 2
 *
 * $var = 1;
 *      Value was apparently 1!
 */

// Creating errors without using exceptions
App_lib::add_notification('info','Info notification');

App_lib::add_notification('error','error notification'); 


Anyone use them like this? If not, why not?