Haswell really is only an iterative upgrade over Ivy Bridge, so I think it's best to get the 3570k over the 4670k. If you intend to game, the 3570k is still a great price
erformance and you could sink the extra cash you would have saved for better graphics, which is what matters most for gaming.
Just do note that when you go with the 3570k, you would need an LGA 1155 socket, Z77 chipset mobo for it.