Mage on T7 PvE

Hey all! I want to ask you if mage is good on this patch on PvE, and if you recommend me rolling one. I love the class but I always played it on ICC with endgame gear, and as far as I know, on Naxx/OS/EoE content you should play Arcane. Although, question is: is it really viable? How much haste should I have? And can I get that number with pre-raid BiS gear to do decent dps on my first raid? Without knowing, I assume you have to be full haste gems and enchants to get there.
Ty in advance for your attention!

Both arc and fire is very viable, fire problably more so because of crit gear in naxx.