I'm hooked on Arabians, but like everyone says it is all in the training. It is important to do a lot of ground work with your horse and introduce the horse to all sorts of things. I had a registered Belgian mare I crossed with my Padron son (Arabian stallion) for a sport horse. Like someone said, sweet, calm mare but not bright. I could always pull up a wheelbarrow and clean out a stall with my Arabs not bothering it, my Belgian mare decided to exit the stall, put her enormous hoof in the center of it and flattened it to the ground. I've told people if I had a barn full of them I'd commit suicide.
I've been disappointed with some of the qualities breeders breed Arabs for these days. Homer Davenport (to long to explain- google it) said when God made the Arabian he made no mistake. The Arabian is supposed to be tough, loyal, brave, kind , intelligent and beautiful, not just beautiful.
Definitely start with an older trained horse, that's great advice.