I disagree with some of these statements.
First you have to ask yourself, what will you get out of a new device which your not getting in your current one?
Now that you've answered this, browse the phones that meet these prerequisites.
Read reviews, see which one has better res., faster processor, whatever meets YOUR needs, not necessarily the markets.
Look at the manufacturors' credentials to get a feel for how well they provide things like updates, support, etc.
Once you've made a decision, go for it. I came from the S4 to this since I bricked it... but typically I will wait a processor generation(1-2 years). Went from having a single core, to dual core, quad core, but f*ed up my phone, so I got a beefed up quad that was appeasing.
WHAT ARE YOUR NEEDS is my main point, sometimes there is never enough processing power for someone who has 5 email accounts, all of the common social networking apps && a high-process running launcher. It all depends on what you do with your device, but 3-6 months after the release of the first generation processor of it's kind is my rule of thumb...
My personal opinion & 2 cents worth. If I knew there was a prime coming out in two weeks from the day I was about to get this phone, I would hold out as well lol