Recently I have been reading a lot about PHP application frameworks, and I’m considering learning one to make my code tidier and more professional.
I’ve heard about symfony, CakePHP and CodeIgnitier.
Is it worth using one of these? If so, where should I start and which should I use?
I’m quite new to this so your help is appreciated 
Absolutely you should try one. If nothing else, it will greatly improve your OOP knowledge. I’d suggest reading the documentation or getting started guide for Symfony (link in my signature). It is well documented and an extremely good framework.
I believe they’re all good frameworks, but I’ve only used symfony to any extent. Agree with AlienDev, go through their tutorials/docs to get an idea. Another one that seems to be gaining popularity is Yii (not done more than glanced at it though).
Sorry, I cannot assess your skills, so don’t be offended, but if you don’t have some already, gain some basic OOP programming knowledge or it may all seem like gibberish to you and you will lose twice as much time wondering how things work like voodoo-magic.
+1
If you have some OOP experience though, I would definitely suggest learning one of these frameworks. Personally, I think the best frameworks around are Zend Framework and Symfony (in no specific order) so any of those two would be great choice. No offense to CodeIgniter but supporting PHP4 these days just doesn’t sound right.
My personal vote goes to Zend
Thanks for your suggestions guys.
In regards to my skills, I’m very experienced programming PHP in a procedural style. I have programmed OO using Java but very little PHP.
I think I will finish reading Sitepoint’s PHP anthology to get familiar with PHP’s OO syntax and then install & read the documentation for symfony.
I would definitely go with symfony. I’ve been using it for the last few months and am now using it on my first project and it’s a great framework. The documentation for it is also fantastic.
My vote goes for Zend.
I am beginner in PHP programming and using DreamWeaver editor. Is PHP Application Framework much easier or difficult.
if you dont understand the basic language constructions in php, then first learn basic and then move to frameworks. It’s actually important to understand the work behind the layers.