I really like my 3570k and I have not even overclocked it yet. My question is will it be enough for the next 2-3 years. I know with mantle in the works and promised of utilizing more core and more threads. the i7 3770k would be a wise choice. As well as it is faster fro editing and other heavily threaded applications. like Cinma4d. I am getting inot editing and will most likely be doing a lot of work on my PC. And I know that I could use the extra oomph that the i7 3770k provides. Or I could get the most out of my i5 for the next few years as I am a casual gamer and I enjoy playing the games maxed out. or I could wait and see what brodwell or skydale has to offer. I will be back tonight so i hope I get some insight on this topic. oh and depending on the circumstance I might go socket 2011 and there are some unknowns with haswell-e right now.
If you are happy with your build now then I can't see an upgrade helping you. The 3770k will become more useful in the next few years but by then something better will be coming out. If you were building now the 3770k would be the choice to make but as an upgrade from the 3570k not so much.