If you are happy with the PW you have just bought and the screen is excellent, it really is debatable whether the extra cost of returning it, and the extra time to wait (another month) for the new one is worth it. Only you can answer that Chi Cygni!
The new one does have a slightly better screen, touch control and processor, but really, a fraction of a second quicker to turn pages, look up words etc? Sure it's good, but it's not a big jump forward, while some (though perhaps not all) of the software improvements may end up being available in the original Paperwhite.
In saying that, I seriously doubt there will be the same issues with dodgy screens and big variations in lighting that Amazon suffered last year. Personally, if I owned a Paperwhite I wouldn't bother upgrading and would rather wait for a bigger jump forward in another years time.
As it is, I plan to upgrade from my Kindle Keyboard (though I do plan on keeping it just in case I miss the page turn buttons too much
), as I want the light in time for the dark, gloomy winter days here in Scotland! I'm just waiting to decide between the PW and the new Kobo Aura.