I have had the Otterbox Defender on my 4s since day one. I haven't had any problems using the screen with the built in screen protector. In my opinion, the Otterbox Defender compliments and protects the 4s very well. I haven't had any manufacture defects. It is holding up. Be careful though, if you take the case off a lot. it will not fit as snug as it did when it was new.
When I get the new IPhone, I will get the same case.