I used to use the bow for roughly 25-30% of all kills, usually for what I would call assassinations, or a lesser group cull. I would rarely use it outside unless I was attacking a group of enemies in a static position.
Now I use both, the bow though has now dropped to 5-10% use and the Crossbow is around 45% use. I keep the bow for novelty kills, and the crossbow is definitely my new primary. It is useful and if you are clever versatile. Plus if you have it drawn and something surprises you, it only takes a flick of the trigger and it is dead, or seriously hurt.
I should point out, most of my kills are from a hidden position (85-90%) and the reload is a great way to wait for suspicion to die down, plus the bash ability is just fun.