What is the best way to test Metal - MBPr late 2012 I just finished upgrading from 10.10 to 10.11 and so far its allot more smooth and responsive. 

I was just wondering if theres any particular games or apps which utilise the new Metal gfx technology which I can checkout now. Anything that really showcases the new technology :) 

I play Guildwars 2 a little, will non Metal games benefit?

And/or is there a way to know if my Macbook is using Metal or not.

Thanks
As yet there aren't any games from the big dev companies utilising Metal, although companies like Blizzard are testing support and will update theirs accordingly in the 'next 6 months'

Those running 10.11 El Capitan can check whether their GPU supports Metal with this app:
Metal Capability Test App