Also, you can install whatever you want on a PC regardless of how old it is. But on iOS you can't download an older version of the app unless you've owned it previously. I do have an iPhone 4 and it's useless because I can't get any apps for it.
Even with the base OS software, you've still got a great music player, a great video player, a multi-function timer/stopwatch/alarm clock, a web browser, a camera, digital maps, a calendar, email, etc.