Running 1/2 Orc Storm Sorcerer level 6... The flight is like a free Misty Step every cast... Keeps them fighters away... Mix that with Shield and another defense item for bonus saves... you get some decent protection to cast your carnage. I found Careful Spell handy ... which i never thought i would. I allows me to push spells through my fighter blockers.
My draconic sorc got flight at level 11 as a class skill, also you can get it with illithid powers, uses up no actions so can use it every round for free.
So I wouldn't say that taking storm sorcery just for flight is worthwhile, just if you prefer the other features.
Also draconic has +3 AC, and my base AC is 16 somehow, if you make human or gith you can also use the +2 AC, +1 spell DC shield.
Oh right, 16 base AC because ?I went 16 dex / 14 con.
Since I'm an elf with no shield, in act 3, 16 base AC is not enough to ever get any shield reactions, so unless you have the means to get base AC to 18 in act 3, I would recommend dropping shield for something else.
I highly recommend human or gith sorc now so you can equip the +1 DC shield with a +1 DC staff, going to do that for my second playthrough, I'm too far into act 3 currently to bother restarting until I've finished and also put up with not realizing I had -2 to 3 stats on Lae'zell from the gith machine.