My roomie has the y50 70 . Good gaming performance but thats all. The build quality is bad. The plastic at the hinges at back and the side plastics which look like lamborghini exhaust have broken in 6 months. The screen is not so bad. ONly noticeable while there is a white background or in surfing or reading , since white color comes kinda creme. Not at all an issue in gaming. Fine color reproduction in that. after sales is also fine and comparable to hp now . In my honest opinion buy the one which gives you the longest warranty . My friend got 3 years onsite, since he bought it at launch. Try to get that , or wait for diwali. That time you will surely get 3 year onsite for free. Dont bother for changing the screens , you will void the warranty which you really would regret in this one.
Oh yeah , his ram also got corrupt within 3 months. But these thing depend on ones luck. Thats what warranties are for. Hp also have some issues sometimes from the beginning.