It depends. There are still a number of releases scheduled on the PS3, and I read somewhere that it is likely they will still be releasing new games for the PS3 for about 2 years after the release of the PS4. So the PS4 was released, what, early 2014? Which means that games should still be released for the PS3 until early 2016.
If you have not had a console recently, then there are literally loads of games on the PS3 which you could play and catch up on. The prices for PS3 games have been dropping very quickly recently, as the next generation PS4 has been released. Conversely, there are not that many games on the PS4 at this time point (or at least not many that I am interested in playing), whereas there are stacks for the PS3.
These are the reasons that I have held off buying a PS4 for the time being, although I already have a PS3. I am also waiting until they work out the 'bugs' both in the games and the console itself, before I buy one. Admittedly, I am not a new adopter of technology either, I prefer to wait a little, and make sure that I am buying something I will really be happy with 
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All I can say is doing some research - plug in "Should I buy a PS3 or PS4?" into Google and you will get heaps of pages to help you decide. And since the PlayStation gaming console is a flagship product for Sony, you can be sure it will still be supported by them for at least a while, even though the PS4 is out. Buying a second hand one is a great alternative, and I certainly will be running 2 consoles at some stage.
HTH