I bought a kindle when they first came into the country - what was that 6 or 7 years ago and it still works fine. I only upgraded to the paperwhite as it was lighter.
The fact that you can take a whole fortnight's reading away with you in one tiny package works for me as half my suitcase used to...
The paperwhite is a really good bit of kit - personally I would say it's worth it (although there's nothing wrong with the previous models)
I upgraded mine a couple of years ago and have been very happy with it