Nope. It's a legit Premier. I can't attest for the quality of the customization, but it looks fine in the photos.
Aside from the recent Stadium Series jerseys (Pens, Hawks, Kings, Ducks), knock offs are not made of Premier jerseys (maybe there are some really obscure examples). They only make Edge knock offs, since Edge jerseys cost twice as much as Premiers at retail.
Even if you don't really know a lot about how to spot counterfeit jerseys, if you see the silver tag in the bottom front corner, along with a made in Indonesia black neck tag, and no fight strap, it's almost certainly legit. There are a few examples of Premiers that are made in Canada like the Senators Heritage Classic jersey, but all the regular Premiers are made in Indonesia.
In short, if it's a Premier that isn't a Stadium Series jersey, it's almost certainly not a knock off, because knock offs aren't made of Premiers (unless there are really obscure ones that I've never seen in my few years of collecting).