It depends on what type of gamer you are, if you are the type that consumes dozens of games per year or just a handful.
If you're really a hardcore gamer who beats dozens of games per year you should stay in current gen and experience all the great PS3 games that are still to come up (GTA5, Castlevania 2, Beyond, Dark Souls II in addition to the cross-gen titles like AC4, BF4 and so on). Then when you have gained enough money to jump into PS4 you will have access to a much larger library of next gen titles to churn through.
But if you typically only play a few games per year you can afford to miss the upcoming current gen games and instead jump into next gen early, since you wouldn't have ever finished many of them anyway.
Myself I'm kinda in the middle. In theory, I imagine I want to experience all the good games that are coming out, 20-25 games per year, but in practice I realize it's impossible and I constantly have to skip titles. That's why I have decided to be more selective with current gen games and jump into next gen early, so I don't ever again get an overwhelming backlog of games I will never be able to complete.