Many are wondering if they should upgrade, well... Depends, I have a 3G and it's really acting buggy lately si I will definetly upgrade! but if you have an iphone 4, perhaps you can wait since it's only been out a year...
I think I might upgrade to the new iPhone 4S because of the camera and the new A5 chip. I have an iPhone 4 and I think it's worth it to upgrade