Er... so as an iOS user you would not care about major updates to the operating system? lol what?
I've used iOS7 a couple of days now on an iphone 4S. I don't notice any performance loss, and the new visuals are nice. Siri is just as retarded as she ever was, the new easy-access swipe upward is nice, added camera features are nice. iTunes radio has excellent sound quality, some of the new UI is kind of hard to catch at first glance due to lower-contrast icons and text being used... that's about it for now. Mixed bag, but mostly positive.
I used mac 10.5 until about six months ago. That OS is old as hell.
Hmm, I'll probably use a jailbroken OS if I ever get one of those.