The arabs are good for a bunch of things... but aren't optimal for anything.
Want to sweep the world with fast moving knights? Arabs are good... chinese are better.
Want to make a 100K culture victory? Arabs are good - Celts or Babylon are better (Celts expand faster, Babylon has more cheap building)
20K victory? Scientific civs are better
I'd go with the conquering style with arabs, myself. Rush to republic, building a bunch of veteran horsemen along the way and expanding, then slowing research enough to build an upgrade treasury as we get to chivalry...
revolt to monarchy, upgrade my horsemen to Ansar's and sweep the world. By that time, the AI should have built a decent road network, so your ansars will be able to get from place to place really, really fast. If you bring along a few pikes to hold taken cities, you can even cut down on losses to counterattacks.