I was in Fallen for two years, joined them right when I started playing regularly.
While relations between NA and EU Fallen were occasionally strained (I may have played a large part in this), we worked together as a unit fairly well. I learned some great battlefield leadership skills from the veterans, and helped bring many new players up to speed. Many EUs I considered my friends, and still do.
Ultimately, leadership was eroding on the EU side, as was their interest in pure cRPG (not strat). Decisions were made with little respect to the views of the NA branch or relative member activity. You were either a regular cRPG player who kept his head down and tried to improve the clan, or some ancient ex-player who held all the power in the world and gazed down upon the battle-server masses with a mixture of nostalgia and stubbornness.
As the NA side became more independent I found myself among the potential leadership for our branch, and made the decision with other active NA members to split. It was intended to be an amicable agreement that NA would essentially remain Fallen, but wear different tags and handle our own internal affairs, but the EU side saw it as an insult and power play.
The result was NA completely splintered, with friendships and a shared TeamSpeak being our only remaining ties to the Fallen. Ultimately I think NA Fallen, now Black Company, has flourished, with our regulars becoming more involved and excited, and recruits entering a more positive, fresh atmosphere.
The few NA Fallens that didn't agree with the decision either remained with the Fallen (but do not play cRPG anymore), or went on their own paths. Fallen as an EU clan appears to be somewhat crumbling, with cRPG interest declining and the same leadership issues that caused the continental divide now slowly killing the clan.
But hey, what do I know?