I expect this'll become the first post of a short series on Zul'Aman. But it might not.
Up until Akil'zon, there's nothing particularly "interesting" for a mage. Pre-Nalorakk trash is pretty normal and the pre-Akil'zon gauntlet isn't that odd either. The main concern about the gauntlet is running out of mana.
Nalorakk is cake. Because of the threat games needed for the tanks to swap between phases, you shouldn't need to worry about aggro after the first transition. Ever. It becomes a fight along the lines of Ragnaros, Patchwerk, Murmur, Lurker Below, etc. You just sit there and shoot.
Akil'zon is more interesting because of the execution elements. If you're lucky, you get assigned to DPS Akil'zon, in which case it's a standard boss fight aside from dealing with the storm. If you're unlucky, like me, you get assigned to anti-eagle duty once they spawn. For me, this tends to be a lot of tab-targeting and praying that Fireball actually works.
Pre-Jan'alai trash is annoying because of the scouts. However, it's just another variant on the pre-Akil'zon gauntlet. The slower you move or the more you linger, the more you're penalized.
Jan'alai is a fight where Fire Ward is extremely useful. (First fight like that I've found since Ragnaros.) Fire Ward can literally save you if your healers are slow on the ball or are having difficulties of their own. Unfortunately, we're still working on trying to figure out this fight.
Pre-Halazzi trash is nice and simple. Halazzi is, in theory, nice and simple too except for totems during phase two. Those totems will kill you. The Flame Shock totem is currently "certain death" for us. Maybe this is an encounter where I'd be better off usng my PvP gear.
Unfortunately, not having downed either Jan'alai or Halazzi, we haven't seen the later bosses in Zul'Aman. I'm looking forward to Hex Lord Malacrass -- just so I can see what he looks like. His yells throughout the zone sound vaguely like they took a troll and stuck him through the same voice filter as they did for the Four Horsemen in Naxxramas.
(I mentioned this to my raid and the paladin tank replied "First kill be mine. Wanna bet?" I was rather amused.)