iOS 7 is the latest version of the operating system designed by Apple Lossless Audio CODEC (ALAC), for iDevices, representing the biggest visual change ever implemented by Apple Lossless Audio CODEC (ALAC), for his creation. This major change in the visual identity also had a hidden "price" felt by the owners of old iDevices, as they had difficulty running in a decent way iOS 7. Even if on iPhone 5S, iPad Air si iPad Mini with Retina Display the operating system runs almost perfectly thanks to the chip A7, on old iDevices things are not so great, in most cases.
I'm starting "from the bottom" and I'll tell you that iPhone 4 is the iPhone you will have worst iOS 7 user experience. Having 3-year-old hardware, Apple's decision to provide support for this terminal is surprising, and if you have the option to buy it, I recommend you avoid it as much as you can. Things are slightly better, but not extraordinary iPhone 4S, this terminal running iOS 7 in good conditions, especially if you activate the option Reduce Motion, disabling most of the iOS 7 effects, on iPhone 4 this option makes the experience bearable to a certain extent. Finally we arrive at iPhone 5 si iPhone 5C, both terminals having approximately the same hardware and the same components, the user experience being close to that of a iPhone 5S and of course you can purchase one of these two terminals without regrets.
In the case of iPad tablets, unfortunately iPad 2 si iPad 3 they have the worst performance in terms of running iOS 7 and activating the function Reduce Motion it doesn't improve things much, so it's advisable to stay away from them. iPad Mini it does not have extraordinary performance with iOS 7, but even if it has the same hardware as the iPad 2, the smaller screen generates less effort for the hardware and implicitly you will have a somewhat better user experience, but not extraordinary. iPad 4 concludes this list and even if we are not talking about an extremely good experience, it is my recommendation for a not very expensive iPad tablet that will allow you to use iOS 7 without any hassle.
Before I finish, I want to tell you that disabling the animations in iOS 7 by activating Reduce Motion will not solve the problems of opening a large number of pages in Safari or a large number of applications in the background. iOS 7 consumes a lot of resources and only iDevices released from 2012 onwards can run it under normal conditions or without any problems, so if you have the opportunity to buy an older iDevice, think seriously about the money you will spend, because you may not be satisfied with the result.
Before I conclude, I will tell you that each smartphone owner "accepts" the functionality of his terminal according to his needs or budget, and the things explained above are based on my experience with the respective terminals.
