I have never had any issues with my iPhone 4 nor have any of the 20 or so friends I know who own one. I have experienced fewer dropped calls and get better reception with the 4 than I got with my previous 3Gs in the same locations even without a case. We've tried to duplicate the "Antenna-gate" problems and been unsuccessful. None have broken their screens. None have scratched them.
What problems with “4” are you referring too? The latest version of the iOS is great for 3GS and iPhone 4 models... no issues that I know of remaining.
If you are referring to the “antenna-gate” loonacy... I was only able to recreate the reception issue on my iPhone 4 by contorting my fairly large hand into an uncomfortable grip of the phone (without a bumper or case). I have found no other issues with mine (have had it a couple of months now).