The galaxy S5 has some amazing features to claim like a 16 MP camera, Octa core proceesor, water and dust proof body, but the phone feels very "plastic" in hand. I owned an S4 before this and felt almost no difference after buying an S5.
I would recommend you to buy Xperia Z2 or wait for iPhone6. You can find my review on the S5 at DealsAndReads.com