Being that this thread is about what to expect about the new expansion. I generally am trying to follow trends set out by the new jobs.
Generally I think it's clear that blue mage:
-Can use a sword
-Can use monster abilities
I think it's reasonable to presume that:
-Blue mage won't have an A+ rating in sword.
-Won't buy scrolls at the AH. <-- I CHANGED IT!!!!!!!!!!!!!!!!!!!!!
-Will have to learn spells.
-Won't have access to the most powerful 1h swords in the game.
-Won't be a direct copy of RDM.
-Will have access to end game armor that is of the same wear as their AF.
The most useful monster abilities that I can think of for a party in a support role are (probably more though):
-healing wind
-whistle
-def down (aoe)
-eva down (aoe)
-acc down (aoe)
-str down (spoil good, bubble shower aoe)
-vit down (leaf dagger)
-mnd down (scream aoe)
-petrify abilities
Although you may say that BLU will be a DD, it's generally expected in this game and in most PT's that if you have a mage hat on and have MP you should be able to heal.
From the last job release, summoner, ninja, samurai, and dragoon, two had major bugs and flaws (note that it took one to two years to fix these), one had continuous changes, and the other with a slight tweak became incredibly nice.
Generally it's assumed that of the new jobs comming out one or two will have major bugs, and one might have an unexpected job function change that will need gear to be added for that purpsose. Regardless it will most likely take one to two years before all the bugs and kinks to be worked out, new equip added, changes to job abilities, and other tweaks to make these jobs of the same calibur as the prior.