| Claxon |
I wouldn't call it super important.
Even at the highest levels its only a +2 bonus to AC unless you spend a move action to "align the shield" against a single enemy.
It's an okay bonus. If you're playing a character that was considering getting extra arms this can give you slightly more reason to do so (pretty much every character is going to use longarms or a two-handed melee weapon, except operatives).
But it's hardly going to make a significant difference in your characters overall survivability.