I have to think you're a troll if you think it feels like the build quality is poor, it feels incredible in hand and you're the first person to say any different.
I have zero lag on the Nexus and I've used my wifes 4S dozens of times so I know the silky-ness of IOS.
I think you're just an Iphone fan man, I really think you're just not cut out for Android. Just being completely honest.
The Nexus is everything we've been waiting for, if it's not for you it's just not for you, doesn't mean the phone's at fault.