Ok, so maybe 'sucks' is a bit strong.... But my question is - Is fire good for anything other than raids?
I re-specced to Fire when I hit 70 and have tried various builds from deep/full fire to arcane/fire etc abut find that for anything other than instances/raids they completely suck.
For farming Primals, PVP or daily quests anything other than full frost is useless.
With Fire you have very little means of survival. With no shield (Ice Barrier) except Mana Shield which is a joke and no means of slowing the mobs before they reach you, mobs at level 70 + take loads of damage from my health meter. And without 'Artic Reach' my Frost Nova is very weak and Ignite usually breaks it after about 2 seconds anyway.
When full Fire I had a variety of stuns such as Blast Wave which does 'daze' the mobs but only at close range. Dragon's Breath, the last talent in the Fire tree, is fairly weak in my opinion. 3 seconds is a measly amount of time to stun a target especially when attempting to fight 2 mobs at one time, which usually results in a dead Mage when I Fire specced.
I usually hit my trinket and start with either Pyro or Fireball (using Combustion if it's not on cooldown) and follow it up with another Fireball, then a Firebast. When the mobs is in range it's then a Frost Nova and back away and another Fireball and another Fire Blast (improved cooldown thru talents) to finish, or a Dragon's Breath to daze the target and another Fireball to finish.
After killing just 2 mobs I have usually lost nearly half my health and at least 3rds of my mana. Even with talents such as Master of Elements and Clearcasting in the mix. I there is no hope of taking more than 2 mobs on at one time without losing pratically all health and mana and Mages are mean't to be king of AOE spells!
With Frost I can grind away for 10 + kills before having to drink or use Evocation. Using frost spells and Ice Barrier when needed which is rare I lose ZERO health when taking on a mob. I easily take on 2 mobs or even 3 using my Elemental and reset all my cooldowns including the Elemental and Ice Block using Cold Snap! And best of all Ice Lance becomes a deadly force in the hands of a Frost Mage! With talents like Shatter and Winter's Chill and Ice Shards I am sure to crit (usually over 4k combined) with a Frostbolt and Ice Lance on a frozen target almost everytime when in comparison using Ice Lance when specced Fire or Arcane is a total waste of time.
So my question is why bother with Fire for anything other than for raiding etc when Ignite and Improved Scorch are great for the extra damage? Get aggro and your chance of survival is next to zero as a Fire Mage and trying to AOE even trash and non-elite mobs solo in an instance without Improved Blizzard to slow attackers is not an option.