My friend had this nike free flyknit 4.0 2015 edition which I used to play hockey. It was one of my best sports shoes that I have used they were relatively very light weight and super flexible.
But if you have 2014 edition then it might be difficult to see any changes in it. Its preety expensive then previous editions.
I love this shoes its very attractive, they are flexible, provide a good fit which avoids slipping, great for running and the best part is you can use it with or without socks. I wound definitely recommend to try this product. But if you are happy with 2014 edition and don’t wana spend too much on this for minor improvements then also yiu are good to go.