iAds aren't actually the only thing added. Your mail was improved, you can make folders, you can make playlists, and now spell checking is incorporated into the native apps. For me, folders is enough to upgrade. And after a day of rigorous personal testing, my whole device seems to be running smoother. You obviously don't see this though.
Why don't you go jailbreak and brick your device.
actually, i've already tried, both things, brick and jailbreak it, unfortunatly, none worked ; )