I have a gen 3 and gen4 g23. I love them both but not enough difference to me to pay the the extra bucks for a gen 4 that may or may not have problems. I have to say that when I took the gen4 out for the first time, the very first shot I fired failed to eject the brass. It takes a lot of shooting to trust a weapon after that happens. I had a couple of other minor problems early on but now it shoots great, good enough that it is my daily carry. The only advantage might be a better fit for a ladies hand with the different back straps but honestly there isn't that much difference. This is not a bash against gen4's, in fact, I have a gen3 g19 and at some point, I will buy a gen4 , not because it is a better gun but because I don't have one. Hope this helps.