Yes, it had better improve Iphones
Every other week a new and improved version of the latest technology and people run out to buy it right away. Then a few days later people complain of all the new problems. Then there comes a new and improved update for the new and improved technology. but the updates are only good if they actually work.
More Than Likely
Apple has declared that the new iOS 7 update will improve performance in iPhone 4's. I have yet to download the update on my phone but given the fact the phone works so slowly from the last update, I don't imagine it can get worse. If it does, I'm clearly going to have to upgrade.
Simpler and Modern.
Yes, I think that the new iOS 7 update will improve performance in the iPhone 4s, because they are finally realizing that we want thing to be more simple and more user-friendly. The iOS 7 is more focused on usability and practicality, rather than the bells and whistles of the iPhone 4.
the new iOS 7 update
I think the new iOS 7 update will improve performance in iPhone 4's. I think that improving the i phone with this update may cause bugs or some types of complications in the beginning but I think overall that if they do use this they will notice big changes in the phone.