Can't give you much info for PvE, but PvP(arena especially) it's not easy at all, first of all you are extremly squishy(a glass cannon) therefore position is the most important thing when playing a mage, second is making proper use of the CC's u got, poly/rof/pet nova you name it, throwing a random poly/rof wont help much, you could do more harm using it randomly(DR). In PvP there's no rotation, because games are different most of the time, sometimes opening with a CC is better than opening with burst and vice versa. I didnt played much PvE but when i did fire was extremly fun, atleast i had fun with it, anyway, cant say i enjoy playing my mage like i did back in wotlk/cata, i felt like u had more sources of dmg and u could play different from others, now u rely on big cd's like ice nova/mirror images, FFB doesnt proc that often, seen it proc once in a 3-4 minute skirmish, u dont got access to mage bombs unless u spec into it which is a big mistake if do so for arenas(atleast for now).. but at the end of the day i couldnt give up on my mage, they are still fun and they will always be, even if the dmg will be crap someday they will still be strong in PvP due to the high amount of CC they can bring.