I am a regular on the DXB-JFK leg and quite often in Y. Y on the A380 with EK is much better than most other Y cabins that I've been into. The cabin itself is very roomy with ample space to amble around and stretch oneself during the flight. Besides ICE, the in-flight entertainment system is fantastic, with an 11 inch widescreen with tons of movies, tv shows, and music on demand.

Try to get seats in the first Y mini-cabin (row 50 or less) - it is the quietest, roomiest, closest to the rest rooms, and the first one to be served. Besides, you'll also be the first ones to dis-embark and so won't have to face a really long queue at immigration.

JFK is a fairly premium heavy segment so my guess is that the paid upgrades to J may not come in cheap. Though, J on the A380 is quite a nice experience overall.