It's usually the simplest things which irritate me - closing/opening an app. Typing on the keyboard. Scrolling down the screen. These things all start to suffer the older a device is. I've got an iPad 2 on iOS7 still for work and it's an absolute nightmare when using numbers etc to view a spreadsheet.Although everyone seems to be worried about the 2 years, I wonder, how long was the IPad 2 sold/supported? Pretty sure it was more than 2 years. Not sure though.
The thing is, many of us who are obsessing over specs, myself included, barely use the current specs. If you only use it for media consumption and web browsing, how 'fast' does it really need to be?
If you 'need' the new features, then IPP is a good choice. If not, it's probably not a good decision.