If you're comfortable using PHP without any framework, then sure it might be time to sample the differences between that and working with frameworks. There are many, many out there to try and for the learning experience it would be better to have a good go at as many different ones as possible.

I'd ignore the person that told you that using a framework would make you be u there with the big guys. Just like using jQuery doesn't make you an expert JavaScript coder, using PHP frameworks won't make you any better a PHP coder. A framework is just a tool, and it's up to your experience to decide which shape the tool should be for any particular job—or if you need one at all—so give a variety of frameworks (don't just stick to the more popular "MVC frameworks" out there) a go.