Right now it's pretty much just a stun. The only difference is your character takes 2 steps one way then 2 steps another way. It really doesn't make a difference in anyway if your hit with fear or stun. I think fear needs it's only little mechanic that matters to add a little more to it from just being another disable.
The obvious thing to do would to make the champion affected by fear run straight away from the source of the fear. This would be useful on shaco but fiddle wouldn't really benefit from it.
Lets brainstorm some ideas to give fear it's own feel kinda like taunt.

lol I feared hemier yesterday, he ran in a straight line at his tower. "So that worked for him."

I agree that the enemy should runaway from the source of fear, but like you said, fiddles wouldn't benefit from fear since he needs to be close to suck away hp.

Make them run away slower?, faster?, uncleansable?

I've both been saved and screwed by running in/out of range while feared, so imo just reduce the ms further so it's closer to a stun, but it still has the fear flavor

If it's just running from the source, doesn't that just make it like a slower knockback?

Not useful to shaco. Would outright break fiddle as keeping people still is required to get use out of drain and crowstorm.

bump

Change it like a little animal that stands still on the road when it sees headlights coming towards it, the fear causes them to not move at all.